Question

1. The inner diameter of a circular well is 3.5 m. It is 10 m deep. Find
0 its inner curved surface area,
(i) the cost of plastering this curved surface at the rate of 40 per m².​

Answer 1

• Given

• Inner diameter of a circular well = 3.5 m
• Depth of a circular wall = 10 m

• To find

• Its inner curved surface area
• Cost of this curved surface at the rate of 40 per m².

• Solution

• Inner curved surface area = 2πrh

where,

• r = radius of the well
• h = height of the well
• Take π = 22/7

• Diameter = 3.5 m

⇒ Radius = Diameter/2

⇒ 3.5/2

⇒ 1.75 m

Substitute the given values,

⇒ 2 × 22/7 × 1.75 × 10

⇒ 110 m²

• Inner curved surface area = 110 m²

(ii) Cost of this curved surface at the rate of 40 per m².

⇒ 110 × 40

⇒ Rs. 4400

• Cost of this curved surface at the rate of 40 per m² = Rs. 4400

Answer 2

ANSWER:

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