How many balls of radius 45 cm can be made by melting a bigger ball of diameter 360 cm?

The ball is in the shape of a sphere. So the properties of a sphere will be applicable here.

Volume of bigger ball = n $$\times$$ Volume of smaller ball

Here n = the number of balls that can be made.

The radius of bigger ball is 'R' and the radius of smaller ball is 'r'.

r = 45 cm

R = $$\frac{360}{2}$$ = 180 cm

$$\frac{4}{3}\pi\ \times\ \left(R\right)^3\ =\ n\times\frac{4}{3}\pi\times\left(r\right)^3$$

$$R^3\ =\ n\times\left(r\right)^3$$

$$\left(180\right)^3\ =\ n\times\left(45\right)^3$$

$$\left(4\times45\right)^3\ =\ n\times\left(45\right)^3$$

$$\left(4\right)^3\ =\ n$$

number of balls that can be made = n = 64