Solution:
Given inner diameter of the brass bowl, d = 10.5 cm
Radius, r = d/2 = 10.5/2 = 5.25 cm
Curved surface area of the bowl = 2r2
= 2×(22/7)×5.252
= 173.25 cm2
Rate of tin plating = Rs.16 per 100 cm2
So total cost = 173.25×16/100 = 27.72
Hence the cost of tin plating the bowl on the inside is Rs. 27.72.