Question

A rectangular pyramid has a volume of 1,512 inches cubed, a height of 12 in., and a base length of 21 in. What is the width of its base?

2 in.
6 in.
12 in.
18 in.

Answer 1

Option D.

Explanation:

The volume of a rectangular pyramid is

`Volume=(1)/(3)lwh`

where, l is the length of the base, w is the width of the base and h is the height.

It is given that

`1512=(1)/(3)(12* 21* w)`

`1512=84h`

Divide both sides by 84.

`(1512)/(84)=w`

`18=w`

The width of its base is 18 in. Therefore, the correct option is D.

Answer 2

Option D. 18 in

Explanation:

Since volume of a rectangular pyramid has a volume = 1512 in³

Height of pyramid = 12 in

Rectangular base having length = 21 in

we have to find the width of the base of pyramid.

Since volume of pyramid =
`(1)/(3)(area of base)(height)`

`1512=(1)/(3)(21.b)(12)`

1512 = 4(21b)

1512 = 84b

`b=(1512)/(84)=18 in`

Therefore width of the rectangular base of pyramid is 18 in

Option D is the answer.