If the radius of a cylinder is doubled and the height is reduced by 50%, then by how much percent does the volume increase/decrease?

100% increase

Let the height and the radius = 10

According to the question,

                                  Before           After

Radius(doubled)            10                20

                                   10               20

Height(5% reduced)       10               5

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

                                 1000             2000 ( 1000) increased)

Percentage increase = 100  ×  \(\frac{100}{100}\) = 100%