# ERRATA - Goswami's Practice Exams (New)



## Jayman_PE

I purchased this text about 1 month ago with high hopes. I am not impressed. After going over both AM exams and the Construction PM exam, I am either

1. An idiot who is taking too long to complete most of these problems.

or

2. The text was poorly written by someone (or people) who did not read the NCEES syllabus and have no concept of what an average 6 minute problem looks like.

So the worry is I may have wasted the equaivalent of 2 to 3 days and money on this text. In short most problems take too long, some are unrelated to the exam (i.e. traffic studies for the AM?), others require obscure equations (i.e. you would probably need the Green Book, etc..., and I'm not a transpo person, to solve.)

There are some good problems in here for sure, but too many take too long. They sort of remind me of the 6 - minute solutions texts and the CERM Practice Problems by Lindeburg. The main difference being those problems are written clearly overall. Anyway, here is what I found so far.

ERRATA

Page 195, Problem 36. Should be 243% increase. (not 143%). Unless I'm mistaken.

Page 37, Problem 120. A lousy question - finding the general relationship for critical velocity/depth for a triangular section. I would like to see if most Civil Hydraulic Professors can solve this inside of 6 minutes? I post this as an Errata because it should be left out of the question set. Maybe a good question for the PM exam, but not AM. Again, 6 minutes.

Page 212, Problem 123. I get V = 6.18 ft/sec. I think Goswami's answer (7.15) works too. Might be a bad coincidence of two intersecting solutions.

Page 40, Problem 126. Did the Author take time to read the NCEES Breadth syllabus for Transportation? Nowhere do I see traffic counts, studies, of any kind. Therefore, this should be removed from the AM and placed in the Transpo PM problem set.

Page 42, Problem 132. See previous statement. Wasted ink.

Page 46, Problem 140. Poorly written. Not clear what we are asked to find: net cost of what? Crashing Schedule option vs. Normal Schedulle?

Again, I have only gone through the AM (#1 and #2) and Construction PM Exams so those venturing further will no doubt uncover more frustration.

thanks,

Jason


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## ptatohed

I bought Goswami's practice exams before his book was published so I received 2 AM exams and 1 PM (Transpo) via e-mailed PDF. Here is what I sent him for the AM Exam #1. (I didn't have enough time to get to the AM exam #2 nor the PM exam before taking/passing the exam in April '11)

In the question 102 diagram, the elevation text overlaps with the tank diagrams

In question 103, remove the "-" before 1.7 inches

In question 112, remove the open parenthesis before A, B, C and D

In the question 123 diagram, change 4 tons to 24 tons

In the question 129 answers A and B, add commas to 2,600 and 3,500

In question 130, add "minimum" after "ladders" in the question

In question 137, indicate the units for the answer choices (inches)

In question 137, correct the spelling of patters to patterns

In solution 101, change 12 &lt;dot&gt; 69 to 12.69. In solution 103, change 1 &lt;dot&gt; 7 to 1.7 and 185 &lt;dot&gt; 5 to 185.5. In solution 106, change 117 &lt;dot&gt; 4 to 117.4. Etc., etc (There are many other instances on other pages too)

In solution 104, change the exponent "&lt;delta&gt;/3" to "8/3". Also, shouldn't the solution specify if n=nf or if n does not = nf for the d/D?

In solution 106, change the first gamma to gamma &lt;sub&gt; d

In solution 107, it appears that c = 1200. What is c and how is it calculated?

In solution 114, what AASHTO Table is being referred to? (Exh 3-2, pg 115 AASHTO does not include 5%)

In solution 118, a quicker method to calc BODu might be to use BODu ~=1.463 x BOD5

In solution 119, change C&lt;sub&gt;z to C&lt;sub&gt;c.

In solution 122, add a comma after "lb" and before "V", first line


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## PEinVA

Jayman_10x said:


> I purchased this text about 1 month ago with high hopes. I am not impressed. After going over both AM exams and the Construction PM exam, I am either
> 
> 1. An idiot who is taking too long to complete most of these problems.
> 
> or
> 
> 2. The text was poorly written by someone (or people) who did not read the NCEES syllabus and have no concept of what an average 6 minute problem looks like.
> 
> So the worry is I may have wasted the equaivalent of 2 to 3 days and money on this text. In short most problems take too long, some are unrelated to the exam (i.e. traffic studies for the AM?), others require obscure equations (i.e. you would probably need the Green Book, etc..., and I'm not a transpo person, to solve.)
> 
> There are some good problems in here for sure, but too many take too long. They sort of remind me of the 6 - minute solutions texts and the CERM Practice Problems by Lindeburg. The main difference being those problems are written clearly overall. Anyway, here is what I found so far.
> 
> ERRATA
> 
> Page 195, Problem 36. Should be 243% increase. (not 143%). Unless I'm mistaken.
> 
> Page 37, Problem 120. A lousy question - finding the general relationship for critical velocity/depth for a triangular section. I would like to see if most Civil Hydraulic Professors can solve this inside of 6 minutes? I post this as an Errata because it should be left out of the question set. Maybe a good question for the PM exam, but not AM. Again, 6 minutes.
> 
> Page 212, Problem 123. I get V = 6.18 ft/sec. I think Goswami's answer (7.15) works too. Might be a bad coincidence of two intersecting solutions.
> 
> Page 40, Problem 126. Did the Author take time to read the NCEES Breadth syllabus for Transportation? Nowhere do I see traffic counts, studies, of any kind. Therefore, this should be removed from the AM and placed in the Transpo PM problem set.
> 
> Page 42, Problem 132. See previous statement. Wasted ink.
> 
> Page 46, Problem 140. Poorly written. Not clear what we are asked to find: net cost of what? Crashing Schedule option vs. Normal Schedulle?
> 
> Again, I have only gone through the AM (#1 and #2) and Construction PM Exams so those venturing further will no doubt uncover more frustration.
> 
> thanks,
> 
> Jason


I've only done 3/4 of the questions of the AM #1 and found a few errors along the way, I'm waiting to hear back from Professor but I have to agree that some of these questions seem way more complicated than I would expect. Also it's not clear on some of his solutions where he's getting some of his values.

I know the CERM questions are harder than the actual exam questions, but any feedback about this exam book versus the actual questions? I'm confident in structural (my discipline) but after donig some of these water/environment questions in the morning #1, i feel like a dope. :beat:


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## bennyG19

Jayman_10x said:


> Page 37, Problem 120. A lousy question - finding the general relationship for critical velocity/depth for a triangular section. I would like to see if most Civil Hydraulic Professors can solve this inside of 6 minutes? I post this as an Errata because it should be left out of the question set. Maybe a good question for the PM exam, but not AM. Again, 6 minutes.


The equation to solve this is given on page 513 of his book. I don't know if you own his book or not so this may not help.


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## bennyG19

I think he asks for VDS on 122 but solves for VSS in the solution. I emailed him to see if I'm correct or if I'm looking at this wrong.


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## bennyG19

bennyG19 said:


> I think he asks for VDS on 122 but solves for VSS in the solution. I emailed him to see if I'm correct or if I'm looking at this wrong.


I emailed him and, once again, I am an idiot!


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## Jayman_PE

bennyG19 said:


> Jayman_10x said:
> 
> 
> 
> Page 37, Problem 120. A lousy question - finding the general relationship for critical velocity/depth for a triangular section. I would like to see if most Civil Hydraulic Professors can solve this inside of 6 minutes? I post this as an Errata because it should be left out of the question set. Maybe a good question for the PM exam, but not AM. Again, 6 minutes.
> 
> 
> 
> The equation to solve this is given on page 513 of his book. I don't know if you own his book or not so this may not help.
Click to expand...

Benny,

My point is the problem is way over 6 minutes. His problems are based upon the structure of his book, not the structure of the NCEES syllabus. Assume you do not have his book (I do) and you encounter that problem on the exam. What to do? Can't look it up in CERM, it's not there. So you need to derive it. And fast. Not a 6 minute problem, more like a 10-15 minute, unless your a Water Resources pro (I'm not).

Having said that I do like his book. It's a perfect companion to the CERM. If I can't find something in the CERM, or just need clarity, I reach for Goswami's text. It's very good. I just don't care for his sample exams overall. Again, there are very good questions in there, it's just that most take way beyond 6 minutes.

thanks,

Jason


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## ptatohed

Jayman_10x said:


> bennyG19 said:
> 
> 
> 
> 
> 
> Jayman_10x said:
> 
> 
> 
> Page 37, Problem 120. A lousy question - finding the general relationship for critical velocity/depth for a triangular section. I would like to see if most Civil Hydraulic Professors can solve this inside of 6 minutes? I post this as an Errata because it should be left out of the question set. Maybe a good question for the PM exam, but not AM. Again, 6 minutes.
> 
> 
> 
> The equation to solve this is given on page 513 of his book. I don't know if you own his book or not so this may not help.
> 
> Click to expand...
> 
> Benny,
> 
> My point is the problem is way over 6 minutes. His problems are based upon the structure of his book, not the structure of the NCEES syllabus. Assume you do not have his book (I do) and you encounter that problem on the exam. What to do? Can't look it up in CERM, it's not there. So you need to derive it. And fast. Not a 6 minute problem, more like a 10-15 minute, unless your a Water Resources pro (I'm not).
> 
> Having said that I do like his book. It's a perfect companion to the CERM. If I can't find something in the CERM, or just need clarity, I reach for Goswami's text. It's very good. I just don't care for his sample exams overall. Again, there are very good questions in there, it's just that most take way beyond 6 minutes.
> 
> thanks,
> 
> Jason
Click to expand...


I don't have the Goswami practice problem book because I bought his practice exams from him when they used to be e-mailed PDFs but I think you guys are talking about this problem, right? Practice exam No. 2, #120. A triangular channel with 1V:3H sides, Q=10 CFS, S = 0.5%, n = .015, what is the critical velocity?

Yeah, the CERM doesn't have the neat formula that the AI1 has on page 513 (303.42) but this is how I'd solve it using the CERM (I have the 10th edition CERM so my page numbers may not match other editions). Not sure if this would take less than 6 minutes or not in the heat of battle.

Step 1: CERM Appendix 19.E (10th edition page A-41): Q = K (1/n) d^(8/3) S^.5. Rearrange, solve for d. d = [Q (1/K) n (1/(S^.5))]^(3/8). From the table, K = 2.71 and therefore *d = 0.9122 ft*

Step 2: CERM Table 19.2 (10th edition page 19-3): A(triangle) = d^2 / tan &lt; theta &gt; (or, A(triangle) = m d^2). Theta = 18.4 degrees and therefore *A = 2.50 ft^2*

Step 3: CERM equation 19.1 (10th edition page 19-2): Q = V A. Rearrange, solve for V. V = Q / A. *V = 4.0 ft/sec*

I get 4.0 and Goswami gets 3.9.

Do you guys see any errors in my process?


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## Jayman_PE

Hmm I think you're on to something. I haven't used Table 19.2 yet but it looks like I should. I like your style. I would not have thought to take your route but it works and that's what counts.

Thanks for sharing.

Jason


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## Lucky1

The above comments are right to the point about this book. I too had studied considerably prior to purchasing this book and felt my confidence crushed when I started working the problems. Many of the problems are very specific to Goswami's text book versus having anything relative in CERM. The book contains numerous problems that have no resemblance to the NCEES outline and many of the problems take a lot longer and are much more complicated than could ever be done within 6 minutes and this is applicable to the problems for the two morning exams and the construction depth exam I have worked through. There are some good problems in this book; there are numerous errors; problems not applicable and problems that are way too complicated. However, the book has its good points and does make you think and its complexity is the tough love practice needed preparing for next month's exam.


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## civilized_naah

ERRATA

Page 195, Problem 36. Should be 243% increase. (not 143%). Unless I'm mistaken.

*You are mistaken. If the before and after values had been equal and the ratio had been 1.00, would the % increase be 100%?*

Page 37, Problem 120. A lousy question - finding the general relationship for critical velocity/depth for a triangular section. I would like to see if most Civil Hydraulic Professors can solve this inside of 6 minutes? I post this as an Errata because it should be left out of the question set. Maybe a good question for the PM exam, but not AM. Again, 6 minutes.

*I believe ptatohed has answered this.*

Page 212, Problem 123. I get V = 6.18 ft/sec. I think Goswami's answer (7.15) works too. Might be a bad coincidence of two intersecting solutions.

*V = 6.18 ft/sec doesn’t fit the equation*

Page 40, Problem 126. Did the Author take time to read the NCEES Breadth syllabus for Transportation? Nowhere do I see traffic counts, studies, of any kind. Therefore, this should be removed from the AM and placed in the Transpo PM problem set.

*Every page of the official syllabus has the following fine print – **The knowledge areas specified as examples of kinds of knowledge are not exclusive or exhaustive categories.*

Page 42, Problem 132. See previous statement. Wasted ink.

*See previous statement.*

Page 46, Problem 140. Poorly written. Not clear what we are asked to find: net cost of what? Crashing Schedule option vs. Normal Schedulle?

*Agreed. The language could definitely have been clearer. As solved, the word ‘net’ implies cost + bonus – penalties for crashing. *


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## bennyG19

problem 508 from transpo. in the solution he uses equation 404.36 from his book with the spiral angle in degrees. in his book it says to use spiral angle in radians with equation 404.36. Which is it?

AAAARGH!! I'm starting to wonder if I can trust his book at all, and I've been using it instead of the CERM for most of my studying.


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## ptatohed

bennyG19 said:


> problem 508 from transpo. in the solution he uses equation 404.36 from his book with the spiral angle in degrees. in his book it says to use spiral angle in radians with equation 404.36. Which is it?
> 
> AAAARGH!! I'm starting to wonder if I can trust his book at all, and I've been using it instead of the CERM for most of my studying.


benny,

I am nearly certain that spiral curves are not on the exam. Don't waste your time studying topics you won't be tested on. I always skipped the spiral stuff (in CERM, in AI1, in Green Book) and never saw it on the Transpo PM (took twice) nor the CA-Survey.


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## civilized_naah

bennyG19 said:


> problem 508 from transpo. in the solution he uses equation 404.36 from his book with the spiral angle in degrees. in his book it says to use spiral angle in radians with equation 404.36. Which is it?
> 
> AAAARGH!! I'm starting to wonder if I can trust his book at all, and I've been using it instead of the CERM for most of my studying.


Equation 404.36 gives "k = xc - Rc sin thetas = Ls(0.5 - qs2/60)"

If you use the sin thetas version, it doesn't matter whether theta is angles or radians as long as your calculator is set to the right mode. If you use the alternate expression, then you theta must be in radians.


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## Jayman_PE

I agree with ptatohed, highly unlikely sprials are on the exam. Stick to the NCEES syllabus. Anything more is wasted effort. 3 weeks left...


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## thebettersmith

Breadth exam No. 2 - the deflection angle (I) computes to 63.56 degrees using his (and my calculated numbers) - Goswami cites 57.2 degrees ???


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## thebettersmith

Oops - sorry - Prob. No. 130 (page 215 of text).


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## civilized_naah

How is the deflection angle equal to 63.56?


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## thebettersmith

crap - next time check your mode setting (HP 35S) - sorry... Goswami wins!


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## Jayman_PE

Which brings up a good point - we should all know how to change our calculator settings from radians to degrees, visa versa. And shame on us if we don't. What if the batteries fail during the exam and after changing them, we have to change settings back?

thanks,

Jason


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## thebettersmith

Goswami Depth Prob 404 - (Water Resources) - how is it possible to relate concentration of micrograms per liter to a flowrate in cfs - something dosen't seem right here.. shouldn't we be converting MGD to CFS to flow rates to liters per second since the contamination levels are given in micrograms per liter?? The units don't cancel as you have the 3.094x term where 3.094 represents CFS at the plant.


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## thebettersmith

.. I could be just losing it.


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## civilized_naah

thebettersmith said:


> Goswami Depth Prob 404 - (Water Resources) - how is it possible to relate concentration of micrograms per liter to a flowrate in cfs - something dosen't seem right here.. shouldn't we be converting MGD to CFS to flow rates to liters per second since the contamination levels are given in micrograms per liter?? The units don't cancel as you have the 3.094x term where 3.094 represents CFS at the plant.


[Q1(cfs) x conc1 (g/L) + Q2(cfs) x conc2 (g/L)]

---------------------------------------------------------- = average conc (g/L)

Q1(cfs) + Q2(cfs)

Units work, what's the problem?


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## thebettersmith

you're right.. a long day


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## thebettersmith

delta Z for Pump Problem 405 (Depth) on page 106 uses 70' as delta Z - should be 80'


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## Jayman_PE

Good catch. Thanks!


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## civilized_naah

thebettersmith said:


> delta Z for Pump Problem 405 (Depth) on page 106 uses 70' as delta Z - should be 80'


Where? On which page is the 70 ft used?


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## thebettersmith

Jayman_10x said:


> Good catch. Thanks!


 You are not alone ([email protected]) live in MD - we can talk about exam - trepedation (sp) is building but you are not alone.. you sound prepared.. humility is yet the first bud of victory. Rudy


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## thebettersmith

Jayman - I am a Christian, like you.



Jayman_10x said:


> Good catch. Thanks!


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## civilized_naah

civilized_naah said:


> thebettersmith said:
> 
> 
> 
> delta Z for Pump Problem 405 (Depth) on page 106 uses 70' as delta Z - should be 80'
> 
> 
> 
> Where? On which page is the 70 ft used?
Click to expand...

Where is the delta Z = 70 ft? Did not see it ...


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## ptatohed

civilized_naah said:


> civilized_naah said:
> 
> 
> 
> 
> 
> thebettersmith said:
> 
> 
> 
> delta Z for Pump Problem 405 (Depth) on page 106 uses 70' as delta Z - should be 80'
> 
> 
> 
> Where? On which page is the 70 ft used?
> 
> Click to expand...
> 
> Where is the delta Z = 70 ft? Did not see it ...
Click to expand...


^^^

c_n takes this very personally.


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## niles22

Folks, so theres still no official errata for this book?


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## Jayman_PE

You're reading it.


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## Jayman_PE

civilized_naah said:


> ERRATA
> 
> Page 195, Problem 36. Should be 243% increase. (not 143%). Unless I'm mistaken.
> 
> *You are mistaken. If the before and after values had been equal and the ratio had been 1.00, would the % increase be 100%? **OK. *
> 
> Page 37, Problem 120. A lousy question - finding the general relationship for critical velocity/depth for a triangular section. I would like to see if most Civil Hydraulic Professors can solve this inside of 6 minutes? I post this as an Errata because it should be left out of the question set. Maybe a good question for the PM exam, but not AM. Again, 6 minutes.
> 
> *I believe ptatohed has answered this.** I answered back. Move problem to PM Transpo.*
> 
> Page 212, Problem 123. I get V = 6.18 ft/sec. I think Goswami's answer (7.15) works too. Might be a bad coincidence of two intersecting solutions.
> 
> *V = 6.18 ft/sec doesn’t fit the equation. **Depends what version you are reading.*
> 
> Page 40, Problem 126. Did the Author take time to read the NCEES Breadth syllabus for Transportation? Nowhere do I see traffic counts, studies, of any kind. Therefore, this should be removed from the AM and placed in the Transpo PM problem set.
> 
> *Every page of the official syllabus has the following fine print – **The knowledge areas specified as examples of kinds of knowledge are not exclusive or exhaustive categories. **Are you a friend of Goswami and/or relative? **I don't work on potential. Only the facts are important.*
> 
> *If we follow your logic then let's just add specs from the Green Book into the AM and every PM depth even though it's not a listed reference for anyone other than Transportation. In doing so we'll add stuff like traffic counts and studies. Wrong.*
> 
> Page 42, Problem 132. See previous statement. Wasted ink.
> 
> *See previous statement. **See previous statement.*
> 
> Page 46, Problem 140. Poorly written. Not clear what we are asked to find: net cost of what? Crashing Schedule option vs. Normal Schedulle?
> 
> *Agreed. The language could definitely have been clearer. As solved, the word ‘net’ implies cost + bonus – penalties for crashing. *
> 
> *I don't care how he/his graduate student solved it. After reading the problem I immediately discounted it.*


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## civilized_naah

You need to calm down for the test! If you keep calm, this test is easy.


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## terzaghi83

This book has way too many errors.


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## civilized_naah

There has yet to be ONE legitimate ERROR named in this string


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## terzaghi83

The author/ publisher didn't waste their time properly reviewing the book. I'm not going to waste my time doing the editor's job.


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## terzaghi83

I've found several in the geotech depth module


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## terzaghi83

problem 304- error in calculation of Ka, problem 315-0 error in calculating depth from bottom 2/3 of pile length to middle of clay layer being compressed, problem 337- error- shouldn't square y 1 and y2 terms in solution, problem 339- error- shouldn't us Ca for group pile skin friciton (just use cohesion, no alpha reduction like with single pile).

I think there were a couple more as well, but the above shows that 10% of the geotech solutions are wrong. This is not helpful at all when trying to prepare for an exam!


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## ptatohed

civilized_naah said:


> There has yet to be ONE legitimate ERROR named in this string


I thought I had a couple of legit errors (yes, many are just formatting/presentation) in post #2, no? But, again, I was using the e-mailed PDF practice exams. Maybe the published book addressed these few errors. I wouldn't worry about the comments here c_n. Everyone is under a lot of stress at this time, a day or two before the exam. After they pass, they'll forget all about any negative comments they might have had and will only have positive comments for this book.


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## Jayman_PE

civilized_naah said:


> There has yet to be ONE legitimate ERROR named in this string


Wrong. Try reading your own book Dr.


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## Jayman_PE

Hey Dr.,

Not one legitimate error? In addition to what's posted above, apparently the following aren't legitamate errors either


Page 251, Problem 304. Solution gives angle of friction = 0, yet question gives friction angle = 15. I get ka=0.5, not 0.34.

Page 17, Problem 31. Problem assumes bucket capacity @ loose measure. Only the truck would have loose measure, not bucket. Thus, no. of days = 9.

Page 322, Problem 616. Total cost is wrong, because truck operational cost is wrong, because total truck hours are wrong. I'll leave it to you to explain why this is not a legimitate error.



Thanks,

Jason


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## Jayman_PE

None of this is meant to wage a personal attack of any kind toward the author. The last I checked there is no law against composing a subpar book. It's just frustrating when we are all trying so hard to study, and pay a lot money for these books. This book is not unique. Korman's Construction Depth and Huang's 6 minute construction solutions are worse than this one. Huang has at least 12% of the problems wrong in her book, and I am sure I missed one or two along the way. I am not counting grammar errors - who cares. I can overlook a few issues here and there, but these are major errors that suggest minimal proofing prior to publication.

Again, nothing personal against anyone here. I'm sure the Dr. is a great person. But when you charge good money you should produce a good product.

thanks,

Jason


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## civilized_naah

I am going to respond even though I am pretty sick of the tone that this conversation has taken. This is just so, whatever is within my powers to clarify, I will clarify, ahead of the upcoming exam. The ONLY ones that merit a response (IMHO) are shown below:

Problem 31. Problem assumes bucket capacity @ loose measure. Only the truck would have loose measure, not bucket. Thus, no. of days = 9.

RESPONSE:

So when soil is dug up and released from confining pressures, there is no bulking?

Problem 140. Not clear what we are asked to find: net cost of what? Crashing Schedule option vs. Normal Schedule?

*RESPONSE:*

*Agreed. The language could definitely have been clearer. As solved, the word ‘net’ implies cost - bonus + penalties for crashing.*

Problem 304. Solution gives angle of friction = 0, yet question gives friction angle = 15. I get Ka=0.5, not 0.34.

*RESPONSE:*

Angle of friction between BACKFILL soil and wall stem is taken to be zero. It is not specified and does NOT have to be the same as the angle of friction between the NATIVE soil and the wall footing, which is given as 20 (not 15). There does not seem to be any error in the value of Ka

Problem 315: Error in calculating depth from bottom 2/3 of pile length to middle of clay layer being compressed, …

*RESPONSE:*

THANK YOU FOR THIS CORRECTION

The thickness that will consolidate is 23.33 ft thick, with center 11.67 ft below point of load transfer. The corrections are:

Delta p = 342.6

P2 = 4697.6

Settlement = 2.6 in

Problem 337- error- shouldn't square y1 and y2 terms in solution,

*RESPONSE:*

WHY NOT?

Problem 339- Shouldn't use Ca for group pile skin friction (just use cohesion, no alpha reduction like with single pile).

*RESPONSE:*

THANK YOU FOR THIS CORRECTION

The diagram for problem 315 should have been used here. The cohesion should be used instead of adhesion.

Problem 616. Total cost is wrong, because truck operational cost is wrong, because total truck hours are wrong.

*RESPONSE:*

THANK YOU FOR THIS CORRECTION

Total truck operating hours = 1134x2.583 = 2929 hrs (was multiplied by just 2 instead of 2.583)

Truck operating cost = 234,330

Total cost = 326,880

Cost per cu yd = 21.79


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## terzaghi83

Problem 337- error- shouldn't square y1 and y2 terms in solution,

*RESPONSE:*

WHY NOT?

According to Both VNS Murhthy and Braja Das texts, these values are not squared for a confined aquifer. They are however, squared in the equation for an unconfined aquifer.

Additional error: in problem 318 solution: resultant earth pressure is listed as 35,513- think it should be 41,313. I think this may just be a math error in the solution and the procedure is correct.

Also- problem 307, shouldn't the solution subtract out the depth of material removed for the mat construction when calculation delta P for settlement equation?

I still think there is an error in the solution to 304. Solution states that rankine's active earth pressure coefficient is Ka is .339. If you use rankine's equation modified for the sloping back fill you get Ka =.311, unless I'm mistaken

Thanks for taking the time to respond. Sorry for negative tone but it is frustrating finding errors in solutions when trying to prepare for an exam, I think I have found a total of 6 errors out of 40 problems (with 1 of them maybe being a simple math error). While trying to learn, you may think you have been doing it wrong all along and the solution is correct, or even worse learning something wrong for the first time (like me trying to compute settlement of the pile group). I spent some time comparing some of the errors to other sample problems and solutions to figure out what was correct and incorrect.

My apologies and Thanks again.


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## terzaghi83

additionally,

I never did understand why in the solution to problem 335 the CSR*effective overburden stress goes in the denominator of the of the FS of equation, yet it goes into the numerator in the 2007 NCEES and 2011 NCEES sample exam. I don't know much about this topic but one must be incorrect.


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## civilized_naah

terzaghi83 said:


> additionally,
> 
> I never did understand why in the solution to problem 335 the CSR*effective overburden stress goes in the denominator of the of the FS of equation, yet it goes into the numerator in the 2007 NCEES and 2011 NCEES sample exam. I don't know much about this topic but one must be incorrect.


I believe in the NCEES question (no. 514 from the 2010 version), the questions states: "maximum allowable cyclic stress ration is 0.29". To me that reads like the cyclic STRENGTH ratio is 0.29. That's why in their solution, they calculate the ULTIMATE shear stress based on this and put it in the numerator of the FS calc. There's nothing wrong with that, except it should not be called the cyclic stress ratio (but they did put the words "maximum allowable" in front of it, so it is kind of OK).

In problem 335, the question states "cyclic stress ration for s design earthquake is 0.21". That means that the actual cyclic shear stress due to this earthquake is to be calculated using the 0.21 value. That's why it belongs in the denominator.

Both are correct.


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## civilized_naah

terzaghi83 said:


> Problem 337- error- shouldn't square y1 and y2 terms in solution,
> 
> According to Both VNS Murhthy and Braja Das texts, these values are not squared for a confined aquifer. They are however, squared in the equation for an unconfined aquifer.


Are you sure, you are not using the version that uses the drawdown values s1 and s2, instead of the water elevation values y1 and y2?


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## civilized_naah

terzaghi83 said:


> I still think there is an error in the solution to 304. Solution states that rankine's active earth pressure coefficient is Ka is .339. If you use rankine's equation modified for the sloping back fill you get Ka =.311, unless I'm mistaken


I have checked this again with a spreadsheet. Linear interpolation from Table 208.1 in the All in One book had yielded Ka = 0.,339, but the exact value I am getting is Ka = 0.334. I am not getting the 0.311 you mentioned. I will check that spreadsheet again, or do it over


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## Jayman_PE

civilized_naah said:


> I am going to respond even though I am pretty sick of the tone that this conversation has taken. This is just so, whatever is within my powers to clarify, I will clarify, ahead of the upcoming exam. The ONLY ones that merit a response (IMHO) are shown below:
> 
> Problem 31. Problem assumes bucket capacity @ loose measure. Only the truck would have loose measure, not bucket. Thus, no. of days = 9.
> 
> RESPONSE:
> 
> So when soil is dug up and released from confining pressures, there is no bulking?


Of course there is release in a bucket volume but not as much as in a truck. When reading the problem that's what I thought was the intent, so I disregarded the swell - thinking it was intended for hauling. So what you are saying is the swell in the bucket is 20%. OK. I would add 2 words to clarify

_The __bucket material__ has the following properties._

Thanks for coming on here and facing the music. Again, no offense intended. Just trying to clarify.

All the best,

Jason


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## terzaghi83

Thanks for the clarification on the seismic issue.

Regarding problem 304: solution states Rankines active earth pressure coefficient is .339. Using the equation in VNS Murhty text for rankines active earth pressure I get .311. Same equation is in both braja das fundamentals of geotech 3rd ed. and pricnciples of foundation engineering 5th ed, yielding same result. Additional, Braja das has a table in both of the referenced books that have values of Ka listed for rankine's condition with sloping backfill. Using slope=15 and phi=34, both tables show Ka=.311. I have confirmed it with equations and tables in two books (allthough it appears that the tables are the same) but I am not sure where the .334 comes from. It would be helpful if the solution showed the calculation to obtain Ka, or where it was obtained from rather than just listing it.

"Are you sure, you are not using the version that uses the drawdown values s1 and s2, instead of the water elevation values y1 and y2?"

I was using the equation in the VNS Murthy text which uses the values y1 and y2 which are measured from the aquifer bottom, and the terms are not squared. I went back and solved it with two different equations- one using the drawdown distances with log in the equation, and another with drawdown distances with natural log in the equation. Not in any of the 3 different confined aquifer equations are the distance terms squared regardless of whether you are measuring height or depth of drawdown. Conceptually, it does not make sense as to why this difference would require squaring in one form but not the other. I get a drawdown of 0.83 feet using all 3 methods, and I think you are incorrect in squaring the distance terms for a confined aquifer regardless of whether measuring drawdown depth or height.

You didn't respond to my question about problem 307, which i think also has an error. Shouldn't the solution subtract out the depth of material removed for the mat construction when calculation delta P for settlement equation? I think goes along the lines of a "fully compensated foundation" where lowering the foundation helps reduce the increase in pressure the soil below is seeing.

Thanks again.


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## terzaghi83

And just to follow up, it truly is helpful that you are taking the time to respond to what may may or may not be errors to help us on the exam tomorrow!

I'm ready for this thing to be over with. Good luck to everyone...


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## civilized_naah

terzaghi83 said:


> Regarding problem 304: solution states Rankines active earth pressure coefficient is .339. Using the equation in VNS Murhty text for rankines active earth pressure I get .311. Same equation is in both braja das fundamentals of geotech 3rd ed. and pricnciples of foundation engineering 5th ed, yielding same result. Additional, Braja das has a table in both of the referenced books that have values of Ka listed for rankine's condition with sloping backfill. Using slope=15 and phi=34, both tables show Ka=.311. I have confirmed it with equations and tables in two books (allthough it appears that the tables are the same) but I am not sure where the .334 comes from. It would be helpful if the solution showed the calculation to obtain Ka, or where it was obtained from rather than just listing it.
> 
> "Are you sure, you are not using the version that uses the drawdown values s1 and s2, instead of the water elevation values y1 and y2?"
> 
> I was using the equation in the VNS Murthy text which uses the values y1 and y2 which are measured from the aquifer bottom, and the terms are not squared. I went back and solved it with two different equations- one using the drawdown distances with log in the equation, and another with drawdown distances with natural log in the equation. Not in any of the 3 different confined aquifer equations are the distance terms squared regardless of whether you are measuring height or depth of drawdown. Conceptually, it does not make sense as to why this difference would require squaring in one form but not the other. I get a drawdown of 0.83 feet using all 3 methods, and I think you are incorrect in squaring the distance terms for a confined aquifer regardless of whether measuring drawdown depth or height.
> 
> You didn't respond to my question about problem 307, which i think also has an error. Shouldn't the solution subtract out the depth of material removed for the mat construction when calculation delta P for settlement equation? I think goes along the lines of a "fully compensated foundation" where lowering the foundation helps reduce the increase in pressure the soil below is seeing.
> 
> Thanks again.


Q 304: I have double checked the spreadsheet and verified the results in there against Table in the All In One book. I have verified multiple values obtained from the spreadsheet versus independent sources. The .334 was obtained by interpolation from the table for Rankine E.P. in the All In One book.

On the aquifer question, if the y is not squared, that equation (All In One eqn 205.23) would not be unit-consistent. Q has units of L^3/T. Right hand side of the equation is L^3/T. If you change the y^2 terms to y, the right side has units L^2/T

Q. 307. You are correct, I forgot to write that one in. The soil removed for the mat corresponds to to a pressure of 399 psf, which should be a reduction of p2


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## terzaghi83

Thanks once again.


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## terzaghi83

After re-looking at things I'm convinced that there must be an error in your table for Rankine's Ka with sloping backfill in all in one book.

Also, while the units are working out in your equation for confined aquifer, I'm still convinced it is incorrect. The confined aquifer equation should have a term in there somewhere for the thickness of the confined aquifer, which will then make the units work out when you don't square the distance terms. See eq. 21.27 in CERM 12 ed, or the Murthy text or braja texts referenced above which all include a term for the thickness fo the aquifer and do not square the distances..

I'm holding to it that there are at least 6 to 7 errors out of the 40 geotech problems, with 1-2 of them being simple math errors and the others being procedural or equation errors that could easily lead someone down the wrong path for the exam.

Many thanks for the responses, I'm traveling to my testing location soon- ready to have this one behind me!


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## civilized_naah

terzaghi83 said:


> Thanks for the clarification on the seismic issue.
> 
> Regarding problem 304: solution states Rankines active earth pressure coefficient is .339. Using the equation in VNS Murhty text for rankines active earth pressure I get .311. Same equation is in both braja das fundamentals of geotech 3rd ed. and pricnciples of foundation engineering 5th ed, yielding same result. Additional, Braja das has a table in both of the referenced books that have values of Ka listed for rankine's condition with sloping backfill. Using slope=15 and phi=34, both tables show Ka=.311. I have confirmed it with equations and tables in two books (allthough it appears that the tables are the same) but I am not sure where the .334 comes from. It would be helpful if the solution showed the calculation to obtain Ka, or where it was obtained from rather than just listing it.


This was bugging me, so I checked Das' Principles of Geotechnical Engineering. Table 10.3 in that book presents Ka values for various combinations of the angles. However, *that table assumes delta = 2/3 phi*. On the other hand, in the problem 304, delta = 0. I have checked the table in the All In One book and it matches the data in Das' table in every way - it just does not make the assumption that delta = 2/3 phi. When I input the condition delta = 2/3 phi into my spreadsheet, the numbers are identical to Das' numbers. So, you can have confidence in the table in the All in One, because it is based on that same spreadsheet.

If you use delta = 0 into the equations, the Ka coeff should be 0.334 (which I got to be 0.339 by interpolation from the All in One table.


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## civilized_naah

terzaghi83 said:


> Also, while the units are working out in your equation for confined aquifer, I'm still convinced it is incorrect. The confined aquifer equation should have a term in there somewhere for the thickness of the confined aquifer, which will then make the units work out when you don't square the distance terms. See eq. 21.27 in CERM 12 ed, or the Murthy text or braja texts referenced above which all include a term for the thickness fo the aquifer and do not square the distances..


No, the exact theory for both unconfined AND confined aquifers is exactly the same - the difference is that for the unconfined one, y refers to the *elevation of the water table* (measured from the aquifer bottom) while for the confined one, y refers to the elevation of the *piezometric surface* (measured from the aquifer bottom). And both of those equations are CERM equation 21.25, in which y is squared. On the other hand, if the aquifer (either type) is very deep (Y &gt;&gt; s), then this can be replaced by the (approximate) equation that includes Y and is written in terms of the drawdown s (linear not squared). This latter approximate equation is 21.26.

Thus, there is no mistake in the solution since it uses the WT elevation.


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## terzaghi83

I will look into the confined aquifer theory as I am assuming you are correct. I am just hoping that it will not be on the exam at this point!

Regarding the earth pressure coefficients: The table I am referring to is table 7.1 in the 5th edition of the foundation book, which is for RANKINE earth pressure (no delta and vertical back wall). The table you referenced is for Coulomb earth pressure coefficients, and assume delta is 2/3 phi as you described (and there is another for delta=1/2 phi.)

The solution states that the RANKINE earth presure coefficient is .33whatever when in fact it is .311. My understanding is that in general, a good rule of thumb is to use rankine's theory for cantilever walls and coulombs theory for gravity walls.

As stated, I appreciate the help.


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## Jayman_PE

Regarding the All-in-One book, I did not have time to post the errata that I found (I bought the book new October 2011), but might also want to check the Nc, Ny, Nq values in the Terzaghi bearing capacity table. I am traveling today and do not have the book with me, but I recall some values being inconsistent with the same shown in Das and CERM 12 Ed.

thanks,

Jason


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## civilized_naah

Jayman_10x said:


> Regarding the All-in-One book, I did not have time to post the errata that I found (I bought the book new October 2011), but might also want to check the Nc, Ny, Nq values in the Terzaghi bearing capacity table. I am traveling today and do not have the book with me, but I recall some values being inconsistent with the same shown in Das and CERM 12 Ed.
> 
> thanks,
> 
> Jason


The Nc and Nq values are perfect. No issues there. There is ongoing controversy about the Ngamma values (which theory is the best predictor). This is why the CERM lists two columns of Ngamma values and says that one of them is according to Vesic's theory. There is also a note to that effect in Das' book. As far as the exams given by the NCEES is concerned, the best thing would be (if these coefficients are not embedded in the question) to use the charts on page 138 of the FE Reference Handbook, because that's THEIR publication. Those match Table 206.2 exactly, by the way. These are called out as "General Bearing Capacity Factors" in both places. Terzaghi's bearing capacity factors are slightly different.


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## Jayman_PE

I'm thinking NCEES would be good enough either tell you which tables to use, or give you the values for the question. No sense in unduly confusing an examinee over trivial matters. Six minutes.

Thanks for clarifying though.

Jason


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## ptatohed

*Edit: Ok, I feel really dumb now. Sin (X) will always equal Sin (180 - X). Please ignore my suggested errata below. Still leaving this post for the suggested equations though. *

I know this thread was started for the Practice Exams book but since the discussion has expanded to the All In One and since Dr. G is nice enough to personally respond - I'd like to confirm what I believe to be errata in the All In One book (1st Ed). I found this last night while helping a friend study.

On page 691, Eqn 404.17 (Topic: Compound Curves, in the Highway Curves, Chapt 404), Shouldn't the "sin /_\ " under the "t1 + t2" really be "180 - sin/_\"? Please confirm.

Also, while not errata per se, I'd like to recommend adding some (in my opinion) crucial formulas for compound curves:

T1 = (R2 - R1 cos/_\ + (R1 - R2) cos/_\2) / sin/_\

T2 = (R1 - R2 cos/_\ - (R1 - R2) cos/_\1) / sin/_\

sin/_\1 = (T1 + T2 cos/_\ - R2 sin/_\) / (R1 - R2)

sin/_\2 = (R1 sin/_\ - T1 cos/_\ - T2) / (R1 - R2)

Thanks!


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## ptatohed

Ok, new errata suggestion. Still helping a friend here at work study. The solution to Transpo depth problem # 504 (LOS question about a 6-lane freeway) shows a fN of 3. But, per the All In One page 713, Table 406.4, and example 406.1, fN should equal 0.0 because the problem statement states that this is a rural freeway segment and all rural segments should have an fN = 0.0. This would give a BFFS of 73.5 (use 75?) instead of 70.5 (use 70) but I don't think it changes the answer of LOS = D.


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## civilized_naah

ptatohed said:


> Ok, new errata suggestion. Still helping a friend here at work study. The solution to Transpo depth problem # 504 (LOS question about a 6-lane freeway) shows a fN of 3. But, per the All In One page 713, Table 406.4, and example 406.1, fN should equal 0.0 because the problem statement states that this is a rural freeway segment and all rural segments should have an fN = 0.0. This would give a BFFS of 73.5 (use 75?) instead of 70.5 (use 70) but I don't think it changes the answer of LOS = D.


I am looking at the solution for #504 and it shows fN = 0 and FFS = 73.5, just as you wrote. Maybe you are looking at a previous (and maybe somewhat different) version?


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## ptatohed

civilized_naah said:


> ptatohed said:
> 
> 
> 
> Ok, new errata suggestion. Still helping a friend here at work study. The solution to Transpo depth problem # 504 (LOS question about a 6-lane freeway) shows a fN of 3. But, per the All In One page 713, Table 406.4, and example 406.1, fN should equal 0.0 because the problem statement states that this is a rural freeway segment and all rural segments should have an fN = 0.0. This would give a BFFS of 73.5 (use 75?) instead of 70.5 (use 70) but I don't think it changes the answer of LOS = D.
> 
> 
> 
> I am looking at the solution for #504 and it shows fN = 0 and FFS = 73.5, just as you wrote. Maybe you are looking at a previous (and maybe somewhat different) version?
Click to expand...

Yes, as peviously mentioned, I have your Sample Exams back when you would e-mail them as PDFs, I do not have the published book. Sorry, I did not know the error had been corrected. Thanks for the response.


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