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

Given, d = 10.5

r = d/2 = (10.5)/2 = 5.25 cm

We know that the Surface area of the hemispherical bowl = 2πr²

using formula,

SA = 2 × (22/7) × (5.25)² = 173.25

Given, Cost of tin-plating 100 cm² area = Rs 16

Therefore, the cost of tin-plating 173.25 cm² area 

= 16 × 173.25 / 100 

= 27.72

Therefore, the cost of tin-plating the inner side of the hemispherical bowl is Rs 27.72.