The volume of a cylinder with a radius of 2 feet and a height of 4 feet is 50.2 feet^3.

The volume of a cylinder with a radius of 4 feet and a height of 8 feet is 401.9 feet^3.
The volume of a cylinder with a radius of 6 feet and a height of 12 feet is 1356.5 feet^3.
If the radius and height are doubled, the volume will be _____ times as large.

A. 27
B. 8
C. 2
D. 4

Wouldn't the answer be 4?

What does doubled mean Johnny? If you double something how much bigger is it going to get?

Multiplied by 2?

Yes johnny

No Abbies

yes Johnny when you double something your multiplying it by 2

since V = pi(r^2)h

if we double r and h
new V = pi(2r)^2(2h)
= 8pi r^2 h

so it increased 8 times

or, since they gave you the volume after doubling in the second sentence, just divide
401.9/50.2 = 8.0059... or 8 times

or

volume of similar objects varies directly with the cube of their sides
2^3 : 4^3
= 8 : 64
= 1 : 8

Thanks for the help Reiny