# The diameter of a sphere is decreased by 25% By what per cent does its curved surface area decrease?

2
Log in to add a comment

Log in to add a comment

so curved surface area = 4πd²/4 = πd² unit²

so the diameter is reduced by 25 % so new diameter = d x 75/100 = 3d/4

so new radius = 3d/8

so new surface area = 4. π. 9d²/64 = 9πd²/16 unit²

so the percentage difference = 9πd²/16/πd² x 100 = 9/16 x 100 = 225/4 = 56.25 %

so total decrease = 100 - 56.25 = 43.75 %