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 ?
Height of cylinder (h) = 1 m = 100 cm
Diameter of box = 140 cm
∴ Radius (r) = 1402 = 70 cm
∴ Sheet required (in m2) to make cylindrical tank = Total surface area of the cylindrical tank
= 2 π r (h + r)
=2×227×70(100+70)cm2
= 440×170 cm2
=74800 cm2
=74800100×100 m2
=7.48 m2