Question

The radius of a spherical balloon increases from 3 cm to 6 cm when air is being pumped into it. Then, the percentage increase in the surface area of the balloon is

Answer 1

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Answer 2

Given:

Initial radius of the spherical balloon = 3 cm

Final radius of the spherical balloon when air was pumped into it = 6 cm

To find:

The percentage increase in the surface area.

Solution:

We know that surface area of a sphere = 4πr²

Initial surface area when  r = 3cm (S1) = 4π(3)² = 36π

Final surface area when r = 6 cm (S2) = 4π(6)² = 144π

Increase in surface area = Initial surface area - final

= 144π - 36π = 108π

Percentage increase = (108π*100) / 36π  = 300%

Therefore the percentage increase in surface area is 300%.