Question

The radius of the base of a right circular cylinder is tripled and the height is doubled. What is the ratio of volume of the new cylinder to that of the original cylinder?

Answer 1

Let the radius of base of the original cylinder = r
And the height of the cylinder = h
Volume of original cylinder = π r² h
Given that, the radius of new cylinder = 3r
And, height = 2r
∴ Volume of new cylinder 
= π x (3r)² x 2h
= 18π r²h
Ratio of volume of new cylinder to that of original cylinder

= `(18π"r"^2"h")/(π"r"^2"h")`
= 18 : 1.