geometry
posted by christina .
jo was comparing two cylinders that both had a radius of 5cm. the first had a height of 10cm, and the other a height of 20cm. How many times greater was the volume of the larger cylinder?

V = pi * r^2 * h
V = 3.14 * 5^2 + 10
V = 3.14 * 25 * 10
V = 785 square cm
That's the smaller cylinder.
Find the volume of the larger cylinder and then subtract.
http://www.mathsteacher.com.au/year9/ch14_measurement/18_cylinder/cylinder.htm 
The volume of the smaller cylinder is 785 cubic centimeters.

v1 = pi r^2 H1
v2 = pi r^2 H2
v2/v1 = H2/H1  twice