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Twenty seven solid iron spheres, each of...

Twenty seven solid iron spheres, each of radius r and surface area S are melted to form a sphere with surface area `\ Sprimedot` Find the (i) radius `rprime` of the new sphere, (ii) ratio of `S"\ "a n d"\ "Sprimedot`

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The correct Answer is:
(i) `R=3r`
(ii) `s:s'=1:9`
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