The number of solid spheres, each of diameter 6 cm that can be made by melting a solid metal cylinder of height 45 cm and diameter 4 cm is (a) 3         (b) 5            (c) 4            (d) 6

Explanation

Volume of sphere` v=frac{4}{3} pi r^{3}`


`rv=frac{4}{3} times frac{22}{7} times 3^{3} cm^{3}`

`
r=4 times pi times 9=36 pi {cm}^{3}`


cylinder volume ` =pi R^{2} h=pi times(frac{4}{2})^{2} times 45 cm`

`
v=180 pi cm^{3}`

`
n=` number of spheres `=frac{v}{V}=frac{180 pi cm^{3}}{36 pi cm^{3}}`

`
Rightarrow n=5`