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 cylinder (h) = 1 m = 100 cm

Diameter of box = 140 cm

$\therefore$ Radius (r) = $\frac{140}{2}$ = 70 cm

$\therefore$ Sheet required (in $m^2$) to make cylindrical tank = Total surface area of the cylindrical tank

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

$=2\times \frac{22}{7}\times 70(100+70)c{m}^2$

= $440\times 170c{m}^2$

$=74800c{m}^2$

$=\frac{74800}{100\times 100}{m}^2$

$=7.48m^2$