Question

27 solid sphere each of radius 2cm are melted to form a ne solid sphere. what will be the surfac area of new sphere

Answer 1

Volume of 27 solid spheres each of radius 2 cm 
= 27× 4/3 × πr³ = 27 × 4/3 × π(2)³ = 27 × 32π/3  = 288π 

Volume of new solid sphere = volume of 27 solid spheres 
4/3 × πr³ = 288π
r³ = 288π×3/4π = 216 
r = ∛216 = 6 cm

Surface area of new sphere of radius 6 cm
= 4πr² = 4π(6)² = 452.39 cm²    Ans.

Answer 2

Volume of 27 solid spheres each of radius 2 cm = >27× 4/3 × πr³          = >27 × 4/3 × π(2)³ = >27 × 32π/3  = >288π 

Volume of new solid sphere = volume of 27 solid spheres 
4× πr³/3 =>288π
r³ = 288π×3/4π = >216 
r = ∛216 = >6 cm

Surface area of new sphere of radius 6 cm = 4πr² = 4π(6)² = 452.39 cm²