Multiple choice

If the height of a cylinder is increased by 20% and the radius of the base is decreased by 10%, then by what percent will its curve surface area change?

  1. 4%

  2. 6%

  3. 8%

  4. 11%

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Original CSA = 2πrh. New height = 1.2h, new radius = 0.9r. New CSA = 2π(0.9r)(1.2h) = 2πrh × 1.08. Change = 8% increase. Percentage change = (new - original)/original × 100 = 8%.