A brass hemispherical bowl has an inner diameter of 10.5 cm. If the cost of tin-plating the inner surface is ₹15 per 100 cm², what will be the total cost (in whole number) of plating the inside of the bowl?
Show answer & explanation
Correct answer: A
Explanation
Dia = 10.5 cm ⇒ r = 5.25 cm
Rate = ₹15 per 100 cm²
According to the formula:
Internal area of hemisphere = 2πr²
Area = 2 × 22/7 × (5.25)²
= 2 × 22/7 × 27.5625
= 173.25 cm²
Cost = (173.25/100) × 15 = ₹26