Multiple choice

A cylinder tub of radius 12 cm contains water up to depth of 20 cm. A spherical iron ball is dropped into the tub and thus the level of water is raised by 6.75 cm. The radius of the ball is-

  1. 4.5 cm

  2. 6 cm

  3. 9 cm

  4. 7.25 cm
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The volume of the spherical ball equals the volume of displaced water. Volume of water raised = π×12^2×6.75 = π×144×6.75 = π×972. Equating to (4/3)πr^3 gives r^3 = 729, so r = 9 cm. Option C is correct.

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