The dimensions of a solid iron cuboid are 4.4 m x 2.6 m x 1.0 m

The dimensions of a solid iron cuboid are 4.4 m x 2.6 m x 1.0 m. It is melted and recast into a hollow cylindrical pipe of 30 cm inner radius and thickness 5 cm. Find the length of the pipe.

Answer

Volume of cuboid = 4.4 × 2.6 × 1 m³ 

Inner and outer radii of cylindrical pipe = 30 cm, 35 cm

$$\text{Volume of material used}=\frac{\pi }{{100}^2}({35}^2-{30}^2)\times h$$

$$=\frac{\pi }{{100}^2}\times 65\times 5h$$

$$\frac{\pi }{{100}^2}\times 65\times 5h=4.4\times 2.6$$

$$h=\frac{7\times 4.4\times 2.6\times 100\times 100}{22\times 65\times 5}$$

$$h=112m$$