Given that internal diameter of hollow hemisphere (r) = 21/2 cm = 10.5cm

External diameter (R) = 25.2/2 = 12.6 cm

Total surface area of hollow hemisphere

Given that cost of painting 1cm^{2} of surface = 10 ps

Total cost for painting 1843.38cm^{2}

=1843.38 x 10 ps

=184.338 Rs.

Total cot to paint vessel all over = 184.338 Rs.