Question

The volume of a cylinder is V = 1/3 πr2h. If the radius is doubled and the height is halved, what will be the ratio of the new volume to the old volume

Answer 1

The answer is 2:1.

Explanation:

New volume/ Old volume = 2 pi divided by pi = 2:1

I took a quiz and this was the answer.

Answer 2

V(o) = 1/3 πr²h - old volume
V(n) = 1/3 π(2r)²(h/2)=1/3 π(2r)²(h/2)=1/3*4/2* πr²h=1/3*2* πr²h
V(n)/V(o)=1/3*2* πr²h/1/3 πr²h=2/1
V(n)/V(o)=2/1 - ratio
the volume will be doubled