Question

Eight metallic spheres,each of radius 2 cm,are melted and cast into a single sphere.Calculate the radius of the new(single) sphere.

Answer 1

volume will be same
8× (2×2×2)=r×r×r
r=4

Answer 2

Radius of 1 metallic sphere = 2cm
volume= 4/3 π r ^3
= 4/3 x 22/7 x 2 x 2 x 2 = 88 x 8/21

volume of 8 spheres = 88 x 8 x 8/21

let the radius of new sphere= y
Volume = 4/3 π y^3
= 4/3 x 22/7 y^3
= 88/21 y^3

88/21 y^3 = 88 x 8 x 8/21
y^3 = 88 x 8 x 8/21 x 21/88
y^3 = 64
y = cube root(64) = 4
y = 4cm.

Hope it helps!!