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A hemispherical bowl has 3.5 cm radius. It is to be painted inside as well as outside. Find the cost of painting it at the rate of ₹ 5 per 10 sq cm. ?
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- ₹ 50
- ₹ 81
- ₹ 56
- ₹ 77
Correct Option: D
Curved surface area of the hemisphere = 2πr2
= 2 x (22/7) x (7/2) x (7/2) = 77 sq
As bowl is to painted inside and outside.
∴ Total surface to be painted = 77 x 2 = 154 sq cm
∴ Cost of painting 154 sq cm = (5/10) x 154 = 1/2 x 154 = ₹ 77
