Question

The inner diameter of a circular well is 3.5 m. It is 10m deep. Find. (1) it's inner curved surface area. (2) the cost of plastering this curved surface at the rate of Rs.40 per m sq.

Answer 1

Answer:

1)110m^2

2)Rs 4400

Step-by-step explanation:

⇒(i)r= radius= 3.5/2=1.75 , h= depth of the well=10m

⇒Curved surface area

=2πrh

(2× 22/7 ×1.75×10)m^2=110m^2

⇒(ii) Cost of plastering = Rs 40 per m^2

The cost of plastering the curved surface = Rs (110×40)= Rs 4400.

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Answer 2

Appropriate Question :-

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• $\textsf{The Inner Radius of a Circular Well is 3.5 m. It is 10 m Deep. Find The Cost of Plastering the Inner Curved Surface at the Rate of Rs. 20/ m²}$

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Required Solution :-

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• $\textsf{Inner Radius (r) = 3.5 m and Height/ Depth (h) = 10 m}$

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀

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

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀

$\textsf{The Inner Curved Surface Area of the Well = 220 m²}$

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀

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

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Hence,

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• $\textsf{The Cost of Painting the Inner Curved Surface Area of the Well is Rs. 4,400 }$

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