The radius and height of a solid cylinder is increased by 5% each. What is the percentage change in its curved surface area?
Answer & explanation
Correct answer: option 4
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%