Question

It is required to make a closed cylindrical tank of height 1 m and base diameter 140 cm from a metal sheet. How many square metres of the sheet are required for the same?

Answer 1

Height of the cylindrical tank, h = 1 m

Radius of the cylindrical tank, r = $\frac{140}{2}$ = 70 cm = 0.7 m (1 m = 100 cm)

∴ Area of the metal sheet required to make the cylindrical tank

= Total surface area of the cylindrical tank

$$\begin{gathered} =2\mathrm{\pi }rh\left(r+h\right) \\ =2\times \frac{22}{7}\times 0.7\times 1\times \left(0.7+1\right) \\ =2\times \frac{22}{7}\times 0.7\times 1\times 1.7 \\ =7.48{\mathrm{m}}^2 \end{gathered}$$
Thus, the area of metal sheet required to make the cylindrial tank is 7.48 m².