A solid metallic sphere of radius 21 cm is melted and moulded into small right circular cones, each of radius 7 cm and height of 3 cm. The number of such cones is:
Show answer & explanation
Correct answer: A
Explanation
The Correct answer is option 1 i.e. 252
Given that
A solid metallic sphere of radius (R) = 21 cm
Let N be small right circular cones, each of radius (r) 7 cm and height of (h) 3 cm
Formula used
The volume of a sphere is = 4/3 π R3
The volume of a cone is = ⅓ 𝜋r2h
Calculation
The volume of a sphere = N × The volume of a cone
4/3 π R3 = N × ⅓ 𝜋r2h
4 × 213 = N × 72 × 3
N = 252