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Two spheres have surface areas in the ratio 4 : 9.
Find the ratio of their radii.

Class 9Surface Area of a SphereMensuration

A2 : 3
B4 : 9
C16 : 81
D3 : 2

Step-by-Step Solution

Surface area is proportional to

r^{2}

, so

r 1^{2} : r 2^{2} = 4

: 9, giving

r 1 : r 2 = 4 : 9 = 2 : 3

.

Answer: A) 2 : 3

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