A hollow garden roller, 63 cm wide with a girth of 440 cm, is made of 4 cm thick iron. Find the volume of the iron.

#### Solution

Given data is as follows:

*h* = 63 cm

Girth is nothing but the outer circumference of the roller, which is 440 cm.

Thickness of the roller = 4 cm

We have to find the volume of the roller.

We have been given the outer circumference of the roller. Let R be the external radius.

We have,

2πR= 440

`2xx22/7xxR=440`

R=70

Also, thickness of the cylinder is given which is 4 cm. So we can easily find out the inner radius ‘*r*’.

r = R - 4

= 70-4

= 66 cm

Now, since we know both inner and outer radii, we can easily find out the volume of the hollow cylinder.

Volume = `pi(R^2 - r^2)h`

`=22/7 xx (70^2 - 66^2 ) xx 63`

`= 22/7 xx 4 xx 136 xx 63 `

Volume = 107712 cm^{3 }