The adjoining figure shows a cuboidal block of wood through which a circular cylindrical hole of the biggest size is drilled. Find the volume of the wood left in the block.

From figure,

Diameter of the biggest hole = 30 cm.

Radius (r) = $\dfrac{\text{Diameter}}{2} = \dfrac{30}{2} = 15$ cm.

Height = 70 cm.

Volume of cuboidal block = l x b x h.

Putting values we get,

Volume of cuboidal block = 70 × 30 × 30 = 63000 cm³.

Volume of cylinder = πr²h.

Putting values we get,

$\text{Volume of cylindrical hole } = \dfrac{22}{7} \times 15^2 \times 70 \\[1em] = \dfrac{22 \times 225 \times 70}{10} \\[1em] = \dfrac{346500}{7} \\[1em] = 49500 \text{ cm}^3.$

Volume of wood left in the block = Volume of cuboidal block - Volume of cylindrical hole = 63000 - 49500 = 13500 cm³.

Hence, the volume of wood left in the block is 13500 cm³.