Question

A rectangle that is twice as long as it is wide forms the base of a rectangular pyramid that is 60cm high. If the volume of the pyramid is 4000 cm cubed, what are the dimensions of the rectangle?

Full show working out ty;)

Answer 1

10 * 20 cm.

Explanation:

Let the width of the base = x, then it's length is 2x cm and the area = 2x^2 cm^2.

Volume = 1/3 * height * area of the base

4000 = 1/3 * 60 * 2x^2

2x^2 = 4000 / (1/3 * 60)

2x^2 = 4000 / 20 = 200

x^2 = 200/2 = 100 cm.

x = 10 cm.

So the dimension of the rectangle = 10 * 20 cm.