Question

The volume of a cylinder varies jointly as the square of the radius and the height. If the volume is 28pi cubic inches when the radius is 2 inches and the height is 7 inches, find the volume

when the radius is 12 inches and the height is 11 inches. Express the answer in terms of pi .
A. 1,728x in
B. 529x in
O C. 1,584x in
D. 1,331x in

Answer 1

1584 cu in.

Explanation:

Since the volume varies jointly with the radius and height we have an equation V = kr^2h where k is the constant of variation

28 = 2^2(7)k = 28k

k = 1

Now V = r^2h

V = (12)^2(11) = 144(11) = 1584 cu in.