# # 112, 123, 124, 132 Electrical and Electronics



## jassiinpublic (Mar 13, 2010)

Hi All, I'm stuck on quite a few problems on the NCEES exam (none that are math heavy, just ones I've forgotten since I graduated).

Here it goes:

112 - I don't understand how both B and D are not the correct answers.

123 (&amp; 524) - If one the inputs is high, does the output of the corresponding not gate pull the common node to 0V? I don't remember TTL. Any good guides out there to refresh basics?

124 - Does anyone have material I can read on Floating Point and the terminology used in this problem?

132 - Same request. Does anyone know where I can read up on oscillators and the circuit shown in this problem?

Thanks in advance guys!


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## rshankle PE (Mar 13, 2010)

jassiinpublic said:


> Hi All, I'm stuck on quite a few problems on the NCEES exam (none that are math heavy, just ones I've forgotten since I graduated).
> Here it goes:
> 
> 112 - I don't understand how both B and D are not the correct answers.
> ...


I don't have the book in front of me, but if you gave more detail on each problem I might be able to help out. (For example I think 132 is the one with the crystal oscillator. It was explained to me that in order for it to be an oscillator the phase in the feedback loop needs to be 0 degrees otherwise you get decay/antenuation in the signal, thus it would not continue to oscillate. So which mode of resonace has 0degree phase? Turns out it is serial.)


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## rshankle PE (Mar 15, 2010)

jassiinpublic said:


> Hi All, I'm stuck on quite a few problems on the NCEES exam (none that are math heavy, just ones I've forgotten since I graduated).
> Here it goes:
> 
> 112 - I don't understand how both B and D are not the correct answers.
> ...


For 112, I posted this in another thread that might help you:

The key here is to realize that linear regression is based upon the coefficients being linear, not the data. In the problem X1, X2, .... represents the data. I had one of our statistics guys come and explain the answer to me. (Even if X1 was logrythmic data, you could let some other variable say X4 = exp(X1) and now follows a straight line.)

The coefficients are bo, b1, b2 ... , so the correct answer is D, because b2 is in the exponent. (That's basically the extent of me understanding that problem.)


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