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.
We know that,
Volume of sphere = 4/3 πr3
Volume of iron ball = 4/3 × 22/7 × 21 × 21 × 21 = 38808 cm3
Volume of spherical ball = 4/3 × 22/7 × 7 × 7 × 7 = 1437.33 cm3
Number of spherical balls = Volume of iron ball/Volume of spherical ball
Number of spherical balls = 38808/1437.33 = 27 balls