The ratio of two spheres is 1 : 2, then the ratio of their surface areas is
The ratio of two spheres is 1 : 2, then the ratio of their surface areas is
A) 4 : 1
B) 1 : 8
C) 1 : 4
D) 8 : 1
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Correct option is (C) 1 : 4
Let radii of both spheres are r and R respectively.
\(\because\) \(\frac rR=\frac12\)
\(\therefore\) Ratio of their surface areas \(=\frac{4\pi r^2}{4\pi R^2}\)
\(=(\frac rR)^2=(\frac12)^2=\frac14\) = 1 : 4
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