If the base radius of a cylinder is doubled, then how many times will its volume become with respect to its original volume?

4

Base radius of cylinder is doubled and height remains same.

Volume of cylinder = π × r² × h

                    Original          New

Radius                 1       :        2

Radius                 1       :        2

Height                  1       :        1

------------------------------------------------

Volume                 1       :        4

So, Volume becomes 4 times of its original.