It is required to make a closed cylindrical tank of height 1 m and base diameter 140 cm from a metal sheet.

Height of the cylindrical tank, h = 1 m

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

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

= Total surface area of the cylindrical tank

$=2 \pi r h(r+h)$

$=2 \times \frac{22}{7} \times 0.7 \times 1 \times(0.7+1)$

$=2 \times \frac{22}{7} \times 0.7 \times 1 \times 1.7$

$=7.48 \mathrm{~m}^{2}$

Thus, the area of metal sheet required to make the cylindrial tank is 7.48 m2.