Question

The radius of a sphere increases by 25%. Find the percentage increase in its
surface area​

Answer 1

Answer:

56.25 %

Explanation:

Let the old radius be R & new radius = R'

New radius = R + R(25/100) = 5R/4

Let the old surface area = 4πR²

Now , New surface area = 4π(5R/4)²

= 25πR²/4

Increase in S.A = 25πR²/4 - 4πR²

= πR²(25-16)/4

= (9/4)πR²

Percentage increase=[(9/4)πR²/4πR²]100

= (9/16)*100

= 56.25 %