Question

A cylindrical tower is 18 metres in diameter and 21 metres high. The cost of white washing its curved surface at ₹ 20 per m2 is ________.​

Answer 1

₹ 33929.20

Explanation:

we are given a cylinder with height 21m and diameter 18m. we can find the radius as
`18/2=9`. next, we will use the surface area formula for cylinders:

`A=2\pi r(r+h)`, where h is our height and r is our radius.

thus, plugging in values of h and r, we get:

`A=2\pi *9*(9+21)=2\pi*9*30=540\pi` square meters.

next, we multiply with the cost/rate of 20.

`C=540\pi*20\approx33929.20` is our cost.