If the radius of a sphere increases by 10 what would be the change in the surface area of the sphere...........

Quantitative Aptitude (CPO) Geometry

If the radius of a sphere increases by 10%, what would be the change in the surface area of the sphere?

This questions was previously asked in

SSC CPO 10th Nov 2022 Shift 3

20%

21%

31%

25%

Alright, let’s walk through this together.

- The formula for the surface area of a sphere is 4pr².

- If you increase the radius by 10%, the new radius becomes 1.1r.

- Plug that in: New area = 4p(1.1r)² = 4p(1.21r²) = 1.21 × old area

- So, that’s a 21% increase in surface area—because 1.21 is 21% more than 1.

Now, about the options:

- Option 1 (20%): Close, but not quite there.

- Option 2 (21%): This one’s spot on.

- Option 3 (31%): That’s too high; maybe confused with volume, not area.

- Option 4 (25%): Doesn’t fit the math here.

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