The number of iron balls, each 1 cm in radius, that can be made from an iron sphere of diameter 12 cm is:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 216
The big sphere has diameter 12 cm, so its radius is 6 cm and its volume is (4/3)π(6)3 = 288π cm3. Each small ball of radius 1 cm has volume (4/3)π(1)3 = (4/3)π cm3.
Dividing, 288π ÷ (4/3)π = 216 balls. The same follows at once from the ratio of the cubes of the radii, 63/13 = 216.