The volume of a cylinder is 100. Another cylinder has twice the height but half the base radius. What is the volume of the second cylinder?

I'm answering the original question

Volume of first cylinder is  given   by

V =  pi * r^2  * h

The volume of the new cylinder is given by

V = p * (r/2)^2 * 2h  =   pi * r^2/4 * 2h  =  [ pi * r^2 * h ]  / 2

So.....the new cylinder has 1/2 the volume of the original = 50