An iron ball of radius 21 cm is melted and recast into spherical balls of radius 7 cm.
Find the number of spherical balls.
Show answer & explanation
Correct answer: D
Explanation
The correct answer is Option 4 i.e. 27
Given that
The radius (r) of an iron ball is 21 cm
The radius (R) of a spherical ball is 7 cm
Let the n number of spherical balls recast from melting of an iron ball
Formula used
The volume of sphere (V) = 4/3 π r³
According to the question
Volume of an iron ball = Volume of n spherical ball
⇒ 4/3 π r³ = n × 4/3 π R³
⇒ 213 = n × 73
⇒ n = 3 × 3 × 3 = 27