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

Explanation

Metal sheet required to make a closed cylindrical tank = Curved surface area of cylinder + 2*Base area of cylinder

`= 2pirh+2pir^2=2pir(r+h)`

Here, `r = d/2 = 140/2 = 70cm = 0.7m`

`h = 1m`

So, required area, `A = 2**22/7**0.7(1+0.7)`

`A = 4.4**1.7 = 7.48m^2`

So, `7.48m` square metres of the sheet are required to make the given cylinder.