A hemispherical bowl has 3.5 cm radius. It is to he painted inside as well as outside. Find the cost of painting it at the rate of Rs.5 per 10 sq cm.
Correct Answer: Description for Correct answer:
Curved surface area of the hemisphere
= \( \Large 2 \pi r^{2} = 2 \times \frac{22}{7} \times \frac{7}{2} \times \frac{7}{2} = 77 sq cm \)
As bowl is to be painted inside and outside
Therefore, Total surface to be painted
= \( \Large 77 \times 2 = 154 sq cm \)
Therefore, Cost of painting 154 sq cm
= \( \Large \frac{5}{10} \times 154 = \frac{1}{2} \times 154 = Rs.77 \)
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