**A lead pencil consists of a cylinder of wood with a solid cylinder of graphite filled in the interior. The diameter of the pencil is 7 mm and the diameter of the graphite is 1 mm. If the length of the pencil is 14 cm, find the volume of the wood and that of the graphite.**

**Solution:**

Diameter of the pencil mm

Radius of the pencil mm **= **0**.**35 cm

Height of the pencil cm

Volume of pencil ** (1)**

Diameter of graphite mm = 0.1 cm

Radius of graphite cm

**Volume of graphite** **(2)**

Subtracting **(2)** from **(1)**, we get

**Volume of wood** = Volume of pencil - Volume of graphite