Question

a cuboid of lenght 16 cm ,breath 12 cm ,height 20 cm is melted down to form a sphere fin the radius of the sphere

Answer 1

Since volumes will remain unchanged , therefore ,

lbh = 4/3 πR³

16×12×20 = 4/3 π R³

3840 × 3 / 4 =π R³

2880/π = R³

Answer 2

volume of cuboid               =   volume of sphere 
Length × Breadth × Height  =   4/3 r cube
16×12×20                          =   4/3 x 22/7 x r x r x r
3840                                  =  88/21 x r x r x r
3840 x 21/88 =r x r x r
80640/88 =r x r x r
916.36 = r cube