2021 · Q57
If W1 and W2 are weights of two solid iron balls of radii ½ metre and 1/3 metre respectively, then which one of the following is equal to W1 : W2?
General Mental Ability, Quantitative Aptitude and StatisticsNumber system and arithmetic
- A8: 27
- B27: 8
- C4:16
- D16:4
Explanation
Weight = Volume x Density Both balls are of same material, hence Weight ∝ Volume. Volume of ball = (4/3)πR³ R = Radius of the ball W ∝ (4/3)πR³ As (4/3)π are constant => W ∝ R³ => W₁ ∝ (1/2)³ => W₂ ∝ (1/3)³ => W₁ / W₂ = (1/2)³ / (1/3)³ => W₁ / W₂ = (3/2)³ => W₁ / W₂ = 27/8 => W₁ : W₂ = 27 : 8