Question

Q16. The inner radius of a
circular well is 3.5 m. It is 10 m
deep. The cost of plastering
inner curved surface at the
rate of Rs 20 per m?is *​

Answer 1

Question :-

The Inner Radius of a Circular Well is 3.5 m. It is 10 m Deep. Find

The Cost of Plastering the Inner Curved Surface at the Rate of Rs. 20/ m²

Solution :-

Given, Inner Radius (r) = 3.5 m and Height/ Depth (h) = 10 m

Then, $\begin {aligned} \red {\bold {Inner\: Curved\: Surface\: Area\: of\: the\: Well}} & = \red {\bold {(2 \pi rh)\: sq.\: units}} \\\\& \Rightarrow 2 \times \frac{22}{7} \times 3.5 \times 10\\\\& \Rightarrow \frac{44}{7} \times 35 = \red {\bold {220\: m^2}} \end {aligned}$

The Inner Curved Surface Area of the Well = 220 m²

$\begin {aligned} \red {\bold {Cost\: of\: Painting\: the\: Inner\: Curved\: Surface\: Area\: of\: the\: Well}} & = Rs. (20 \times 220)\\\\& = \red {\bold {Rs.\: 4,400}}\end {aligned}$

Hence,

The Cost of Painting the Inner Curved Surface Area of the Well is Rs. 4,400 . . .

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