Question

44. The internal and external diameters of a hollow hemispherical vessel are
10 cm and 11 cm respectively. If the cost of painting 1 cm² of the surface
area is 0.05, find the total cost of painting the vessel all over.
17​

Answer 1

Answer:

ANSWER

Internal diameter of spherical vessel =24 cm

External diameter of hemispherical vessel =25 cm

Internal radius =r=12 cm and External radius =R=12.5 cm

Total surface area to be painted

= External curved surface + Internal curved surface + Area of ring

=2πR2+2πr2+π(R2−r2)

=π(2R2+2r2+R2−r2)

=π(3R2+r2)

=722(3×12.52+122)

=722(468.75+144)

=722×612.75

=1925.78sq.cm

Rate of painting =5paise per sq.cm

Thus, cost of painting=Area×Rate=1001925.78×5=Rs.