Math Destroyer 2013 PT 6 #15

Started by Tajlrak
This forum made possible through the generous support of SDN members, donors, and sponsors. Thank you.
Get help with your application

Use all the free resources available to you from SDN: articles, guides, expert advising, forums discussions, and school research.

Tajlrak

Full Member
10+ Year Member
Advertisement - Members don't see this ad
I was wondering what is your approach to this problem.

How many different rectangular prisms having a volume of 30ft^3 are there with sides that are each an integer number of feet?

3
4
5
6
7

A: 5

Thanks in advance.
 
I recall this one being confusing at first, then I just decided to write them out.

Area = L*W*H

Options: 1,2,15; 1,3,10;1,5,6;2,3,5;30,1,1 I think are the only options, so that's 5. I think I was confused because I didn't immediately realize 1,2,15 is the same as 2,1,15.

A lot of the time on these problems I try and set up some formula when you can actually deduce a great deal from the answer key.
 
I recall this one being confusing at first, then I just decided to write them out.

Area = L*W*H

Options: 1,2,15; 1,3,10;1,5,6;2,3,5;30,1,1 I think are the only options, so that's 5. I think I was confused because I didn't immediately realize 1,2,15 is the same as 2,1,15.

A lot of the time on these problems I try and set up some formula when you can actually deduce a great deal from the answer key.

Cool deal and I see how u wrote it all down. I guess what I am trying to get at is when we are under time constraint and we are writing down all the possible ways, is there a clear cut way to know that you wrote out all the solutions so you wont be 2nd guessing your self? I do not think so.. which is why i this question is bugging me.
 
Not that I know of. I'm not great at math, and the explanation in the back didn't really help me per se...This is one of those times I do it the long way. At worst, guess, mark it, and move on.