The inner diameter of a well is 2.5 metres and it is 8 metres deep. What would be the cost of cementing its inside at 350 rupees per square metre?

Given: inner diameter of a well “d” = 2.5m

Depth(height) of the well “h” = 8m

Cost of cementing = 350 rupees per square meter

To find : total cost of cementing the inner well

Procedure :

First, we will have to find the inner lateral surface area of the well.

And for that area we will have to find the cost of cementing.

So, lateral surface area of the well = perimeter of base of cylinder × height of cylinder

Now inner diameter = 2.5m

So, inner radius of the well = = 1.25m

Now, lateral surface area of the well = 2∏× radius × height of the well

⇒lateral surface area of the well = 2∏× 1.25 × 8

= 2× 3.14× 1.25× 8

lateral surface area of the well = 62.8m²

now, the cost of cementing for this inner lateral surface area will be, lateral surface area of the well× cost per square meter

so, the total cost of cementing = 62.8× 350 = 21,980 rupees

∴ the total cost for cementing the inner walls of the well is 21,980 rupees.