Twenty cylindrical pillars of the Parliament House are to be cleaned. If the diameter of each pillar is 0.50m and height is 4m. What will be the cost of cleaning them at the rate of Rs. 2.50 per square meter?

Explanation

Number of pillars`=20`
Diameter of one pillar`=0.50`
`∴`Radius `(r)=0.50/2=0.25m`
Height `(h)=4m`
Curved surface area of one pillar`=2pirh=2xx22/7xx25/100xx4m^2=447m^2`
`∴`Total area of `20` pillars`=44/7xx20=8807m^2`
Rate of cleaning them`=Rs.2.50` per `m^2`
`∴`Total cost:
`=Rs.2.50xx880/7`
`=Rs.(250xx880)/100xx7`
`=Rs.2200/7`
`=Rs.314.28`
Hence, the total cost of cleaning is `Rs.314.28`.