Question

Four cylindrical pillars of a building are to be painted. If the diameter of each pillar is 1.4m and it's height is 6m, find the cost of painting the curved surfaces of all the pillars at the rate of Rs 10 per.sq.m.​

Answer 1

`Rs. 1056`

Explanation:

Given: Diameter of each pillar= 1.4m

Height= 6m

Cost of painting the curved surfaces of all the pillars at the rate of Rs
`10\ per\ m^(2)`

First lets find out radius of each pillar.

Radius (r)=
`(Diameter)/(2)`

∴ Radius (r)=
`(1.4)/(2) = 0.7\ m`

Now, finding area of cylindrical pillar.

Formula; Area of curved surface=
`2\pi rh`

⇒ Area of curved surface=
`2* (22)/(7) * 0.7* 6 = 26.4\ m`

∵ There are four cylindrical pillars.

∴ Curved surface area of four pillar=
`4* 26.4\ m= 105.6\ m^2`

Curved surface area of four pillar is 105.6 m²

Next, finding the cost of painting the pillars.

As given, cost of painting is Rs 10 per m².

∴ Cost of painting 105.6 m²=
`10* 105.6 m^(2) = Rs. 1056`

∴ The cost of painting the curved surfaces of all the pillars is Rs.1056.