If the radius of a cylinder is doubled and so height is made 3 times, what is the new volume of the cylinder divided by the old one?  Select:
A) 8. B) 12. C) 6. D) 4. E) 10.
let v and v' be the original and the changed volume   now   v=pir^2h   v'=pi(2r)^2(3h)   v'=12v   12.) 12
<result>B</result>
If the radius of a cylinder is doubled and so height is made 3 times, what is the new volume of the cylinder divided by the old one?