Question

The internal and external diameters of a hollow hemispherical vessel are 24 cm and 25 cm respectively. The cost to paint 1 cm² of the surface is Rs 0.05. Find the total cost to painting the vessel all over.

(A) Rs 108.32

(B) Rs 296.28

(C) Rs 101.59

(D) Rs 96.28

Answer 1

The correct option is : (D) Rs 96.28

Explanation:

External radius of hemispherical vessel r₁ = 25/2 cm

Internal radius of hemispherical vessel r₂ = 24/2 = 12 cm

External curved surface area of hemispherical vessel = 2πr₁² 

Internal curved surface area of hemispherical vessel = 2πr₂²  

Cost of painting the vessel at the rate of Rs 0.05 per cm² = 1925.78 x 0.05 = Rs 96.28