If the surface area of a sphere is reduced to one ninth of the area its radius reduces to ........

Quantitative Aptitude (CDS) Mensuration 3D

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If the surface area of a sphere is reduced to one-ninth of the area, its radius reduces to

One - fourth

One -third

One - Fifth

One -ninth

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Explanation:

Surface area of a sphere = 4 $\small \pi$ r²
S1 = 4 $\small \pi$ r₁2 ................(1)
S2 /9 = 4 $\small \pi$ r₂² ....................(2)
From 1 and 2
4 $\small \pi$ r₁2 = 36 x 4 $\small \pi$ r₂²
r₁² / r₂²= 9 / 1= 3 /1
So radius is reduced to one third .