devarshi-dt-logo

Question:

A hemispherical bowl made of brass has inner diameter 10.5 cm. Find the cost of tin-planting it on the inside at the rate of 16 per 100 cm².

Solution:

Given: r = 10.5/2 = 5.25 cm
Surface Area = 2πr² = 2 × 22/7 × 5.25 × 5.25 = 173.25 cm²
⇒ Cost of planting 100 cm² area = Rs. 16
⇒ Cost of planting 173.25 cm² area = Rs. 16 × 173.25/100 = Rs. 27.72