The capacity of a closed cylindrical vessel of height 1 m is 15.4 litres. How many square metres of metal sheet would be needed to make it?
Capacity = 15.4 litre = 15400 cubic cm, h = 1 m = 100 cm
Volume of cylinder = π r2 h
Or, 15400 = (22/7) X r2 X 100
Or, r2 = (15400 X 7)/(22 X 100) = 49
Or, r = 7 cm
Now, total surface area of cylinder = 2 π r(r + h)
= 2 X (22/7) X 7 (7 + 10)
= 2 X 22 X 17 = 748 sq cm
