Question
The radius of a spherical balloon is increased by 20%. Find the percentage increase in its surface area.
This question was previously asked in
RRB NTPC 2025 Graduate CBT 2 Question Paper PDF (10-Jul-2026) (Shift 1)
The correct answer is
44%
Surface area is proportional to the square of the radius. With radius increased by 20% (multiplier 1.2): \((1.2)^2 = 1.44\).
Hence, the surface area increases by 44%.
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