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

Answer:

Option D.

Step-by-step explanation:

The volume of a rectangular pyramid is

$Volume=\frac{1}{3}lwh$

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

It is given that

$1512=\frac{1}{3}(12\times 21\times w)$

$1512=84h$

Divide both sides by 84.

$\frac{1512}{84}=w$

$18=w$

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

Answer 2

Answer:

Option D. 18 in

Step-by-step 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 = $\frac{1}{3}(area of base)(height)$

$1512=\frac{1}{3}(21.b)(12)$

1512 = 4(21b)

1512 = 84b

$b=\frac{1512}{84}=18 in$

Therefore width of the rectangular base of pyramid is 18 in

Option D is the answer.