The radius of a cylinder is increased by 120% and its height is decreased by 40%. What is the percentage increase in its volume?

Answer: Option A

Solution

Answer: Option A

Solution:

\begin{array}{*{20}{c}} {}&{{\text{Before}}}&{}&{{\text{After}}}&{} \\ {{\text{Radius}} \to }&5&:&{11}&{120\% \to \frac{{ + 6}}{5}} \\ {{\text{Height}} \to }&5&:&3&{40\% \to \frac{{ - 2}}{5}} \\ {{\text{Volume}} \to }&{{5^2} \times 5}&:&{{{11}^2} \times 3}&{} \end{array}
         
$$\%\text{Increase}\Rightarrow \frac{238}{125}\times 100=190.4\%$$