QR: prism

[joonkimdds]

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how many different rectangular prisms having a volume of 30ft^3 are there with sides that are each an integer number of feet?
a. 3
b. 4
c. 5
d. 6
e. 7


how do I solve this problem?

 

[GOLF]

gah. you got me.

 

[Shinpe]

I'm not sure if i'm understanding the question right, but is C)5 right?

30,1,1 - 15,2,1 - 3,5,2 - 3,10,1- 5,6,1

 

[UCB05]

how many different rectangular prisms having a volume of 30ft^2 are there with sides that are each an integer number of feet?
a. 3
b. 4
c. 5
d. 6
e. 7


how do I solve this problem?

I count 5...

1, 1, 30
1, 2, 15
1, 3, 10
1, 5, 6
2, 3, 5

is that right?

 

[joonkimdds]

C is correct but I don't even know how to start this problem. How did you guys come up with those numbers?

 

[llungu]

A cube is a special type of prism with 6 equal faces. Anyways volume is l * w * h... Does that help?

 

[Shinpe]

C is correct but I don't even know how to start this problem. How did you guys come up with those numbers?

The volume is all 3 sides multiplied by each other. So you look at all the integer factors of 30, aka: 30, 15, 10, 6, 5, 3, 2, 1 and see how many ways you can combine 3 of them to multiply to 30.