Question

Cylinder A has radius r and height h. Cylinder B has radius 2r and height 2h. How many times greater is the surface area of Cylinder B than the surface area of Cylinder A?
I have no idea how to start doing this problem. Are there any tips on how to start?

Answer 1

If it is a closed cylinder, total surface area of Cylinder A = $2\pi r^2h$ + $2 \pi rh$ = $2 \pi r(r+h)$, while surface area of cylinder B is $2 \pi (2r)(2r+2h) = 8 \pi r(r+h)$. Therefore, dividing B by A, the surface area of B is 4 times greater than A.