The radius and height of a solid cylinder is increased by 5% each. What is the percentage change in its curved surface area?

10.25%

C.S.A. of cylinder = 2\(\pi \)rh

5% = \(\frac{1}{20}\)

                     Actual   :     New

Radius:           20       :     21

Height:           20       :     21

C.S.A. :        2\(\pi \)RH    :     2\(\pi \)rh

          :           20²      :      21²  = 400  :  441

⇒ C.S.A. increased by = 441 - 400 = 41

⇒ Increased percentage = \(\frac{41}{400}\) × 100 = 10.25%