The cost of painting the total outside surface of a closed cylindrical oil tank at 60 paise per sq. dm is Rs. 237.60. The height of the tank is 6 times the radius of the base of the tank. Find its volume correct to two decimal places.

Explanation

Let `r` be the radius of the base and `h` be the height of the cylindrical tank.
Then, `h=6r` (given)
Total surface area`=2pir(r+h)=2pir(r+6r)=14pir^2`
Cost of painting`=Rs.(14pir^2)xx(60/100)=Rs.(42/5)​r^2`
The cost of painting is `Rs. 237.60`:
`∴42/5pir^2=237.60`
`⇒(42/5)xx(22/7)xxr^2=237.60`
`⇒r^2=237.60xx(5/42)xx(7/22)=9`
`⇒r=3 dm`
`∴h=6r=18dm`
Hence, volume of the cylinder`=pir^2h`
`=(pixx3xx3xx18)dm^3`
`=(22/7xx9xx18)dm^3`
`=509.14dm^3`