Question

# The inner diameter of a circular well is 3.5 m. It is 10 m deep. Find its inner curved surface area

Hint: - Here we use the formula of curved surface area of cylinder i.e.$2\pi rh$ . As we know the shape of well is the same as the shape of the cylinder so by letting the well as cylinder help us for solving the question.

Given, the diameter of the well is 3.5m and the depth is 10m.
And we let the well as a cylinder whose diameter d=3.5m and height will be h=10m.
Now the radius of cylinder is $\frac{{3.5}}{2} = 1.75m$
Then curved surface area of cylinder $= 2\pi rh$
$= 2 \times \frac{{22}}{7} \times 1.75 \times 10$
$= 2 \times 22 \times 0.25 \times 10$
$= 110{m^2}$
Therefore the inner curved surface area of well is$110{m^2}$.

Note:-Whenever we face such a type of question first write the things that are given in the question then apply the formula of that figure that are given in the question. In this question we know that wells are in the shape of a cylinder so we apply the formula of the cylinder to get the answer.