Solve the problem May 27, 2009

Guest · May 27, 2009

I happened to be reading through some material on optimization solving techniques and read this problem offered up as an example:

A commanding officer (CO) has been tasked to move the battalion out into the field for a major exercise. The CO has been informed that only a maximum of 100 vehicles is allowed, each to be used for a single round trip. There are two types of vehicles available to the CO, a Mack vehicle that can carry 24 m3 and a Mercedes vehicle that can carry 16 m3. The Mack vehicle is estimated to use 50 L of fuel on a round trip, whereas the Mercedes vehicle will only use 25 L of fuel per round trip. The battalion has a total of 4000 L of fuel available. The vehicles will require maintenance after each round trip; each Mack vehicle requires 3 h and each Mercedes 9 h. The maintenance squadron has 720 h available.
To move a maximum amount of cubic meters, what mix of Mack and Mercedes vehicles should the CO choose?

It never ceases to amaze me how someone put together such a completely absurd problem (though the principles may be valid). So ... go ahead ... provide an answer ....

JR

Master slacker · May 27, 2009

5... take it or leave it.

Capt Worley PE · May 27, 2009

The sad thing is there was a time in my life where I could do this without thinking. I seem to recall it has something to do with taking a derivative.

MA_PE · May 27, 2009

for maximum efficiency, use only the Mercedes vehicles - Eurpoean stuff and their methods are far superior to anything American.

Capt Worley PE · May 27, 2009

MA's right. Everything European is better.

jmbeck · May 27, 2009

MA_PE said:
for maximum efficiency, use only the Mercedes vehicles - Eurpoean stuff and their methods are far superior to anything American.

That and they're PIMP!

When's the last time you saw someone wearing a gold plated spinning bulldog?

I didn't think so.

csb · May 27, 2009

80 Mack trucks and 20 Mercedes

edit: totally not possible, because there's no fuel for that scenario...rushed my answer

wilheldp_PE · May 27, 2009

A commanding officer (CO) has been tasked to move the battalion out into the field for a major exercise...a Mack vehicle that can carry 24 m3 and a Mercedes vehicle that can carry 16 m3.

How many cubic meters are there in a battalion?

Capt Worley PE · May 27, 2009

African or European?

Dexman1349 · May 27, 2009

I would normally agree with using the Mercedes, but after owning a German car I can honestly tell you that the added expense fuel from using the Mack would be significanly lower than trying to maintain a Mercedes. Last time I took my VW Jetta in for service it was about $250 for a 60k oil-change.

Use the Macks.

roadwreck · May 27, 2009

Dexman1349 said:
I would normally agree with using the Mercedes, but after owning a German car I can honestly tell you that the added expense fuel from using the Mack would be significanly lower than trying to maintain a Mercedes. Last time I took my VW Jetta in for service it was about $250 for a 60k oil-change.
Use the Macks.

well if you only have to change your oil every 60,000 miles I'd say $250 is a fair price.

Supe · May 27, 2009

Use neither and subcontract out the work.

Dexman1349 · May 27, 2009

roadwreck said:
well if you only have to change your oil every 60,000 miles I'd say $250 is a fair price.

Unfortunately it's every 10k,

10, 30, 50, 70K services are the cheap ones at $130 each

20, 60, 100k are the 2nd most expensive at $250

40, 80, 120k are the retardedly expensive ones at $550 each (after using a 10% coupon and removing the tire rotation from the tasks)

wilheldp_PE · May 27, 2009

Solver Says:

You should use 60 Macks and 40 Mercedes. You could move 2080 cubic meters of stuff using all 4000 L of fuel and 540 hours of maintenance.

Freon · May 27, 2009

I too could solve these things in my sleep a dozen or so years ago during "Systems Optimization" class in grad school. The key is to identify the boundry conditions. I was lazy and wrote a bit of MATLAB code to brute-force out an answer back then. But I'm sure there is a more elegant way to do it.

Freon, feet dry until Friday

SkyWarp · May 27, 2009

Dexman1349 said:
Unfortunately it's every 10k,
10, 30, 50, 70K services are the cheap ones at $130 each

20, 60, 100k are the 2nd most expensive at $250

40, 80, 120k are the retardedly expensive ones at $550 each (after using a 10% coupon and removing the tire rotation from the tasks)

At least the expensive service makes it a reliable brand, oh wait....

Capt Worley PE · May 28, 2009

Dexman1349 said:
Unfortunately it's every 10k,
10, 30, 50, 70K services are the cheap ones at $130 each

20, 60, 100k are the 2nd most expensive at $250

40, 80, 120k are the retardedly expensive ones at $550 each (after using a 10% coupon and removing the tire rotation from the tasks)

HAHAHA Chevy Malibu Maxx--$30 bucks every 5K miles. Suck it, Das Auto!!!!

Freon said:
I was lazy and wrote a bit of MATLAB code to brute-force out an answer back then.

I thought about doing that, but was overwhelmed by apathy.

wilheldp_PE · May 28, 2009

Capt Worley PE said:
I thought about doing that, but was overwhelmed by apathy.

It's not necessary. Takes about 30 seconds to set up the equations, and a minute to put into to Excel Solver.

MA_PE · May 28, 2009

wilheldp_PE said:
Solver Says:
You should use 60 Macks and 40 Mercedes. You could move 2080 cubic meters of stuff using all 4000 L of fuel and 540 hours of maintenance.

Simple Excel Spreadsheet gives the same answer.

Q.) what difference does the maintenance make?

You're only using the trucks for one round trip each. If the trucks require maintenance between each leg then I'd get some new trucks. 3hrs maintenance after burning 25L (6.6 gals) fuel or worse 9 hrs for 12.5L (3.3 gals) fuel tells me these trucks are complete POSs.

Capt Worley PE · May 28, 2009

They are the trucks from The Sorcerer.

Solve the problem May 27, 2009

Help Support Professional Engineer & PE Exam Forum:

Guest

Something awesome.

Run silent, run deep

engine near

Run silent, run deep

Well-known member

Well-known member

PE, LEED AP, SPAM KING

Run silent, run deep

Dexman1349

Probie-one, PE

Well-known member

Dexman1349

PE, LEED AP, SPAM KING

Well-known member

Spread that butter... with the force.

Run silent, run deep

PE, LEED AP, SPAM KING

engine near

Run silent, run deep

Similar threads

Join the conversation!

Join today and get all the highlights of this community direct to your inbox. It's FREE!