A hemispherical bowl made of brass has an inner radius of 3.5 cm. Find the cost of tin plating it on the inside at the rate of ₹4 per cm2.
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1, i.e., ₹308.
Inner radius of hemisphere, r = 3.5 cm
Rate of tin plating = ₹4 per cm2
Curved surface area of hemisphere = 2 × π × r2
⇒ CSA = 2 × (22/7) × 3.5 × 3.5
⇒ CSA = 2 × (22/7) × 12.25
⇒ CSA = 2 × 38.5 = 77 cm2
⇒ Cost = 77 × 4 = ₹308