A cylinder is partially filled with water. Two iron spherical balls are completely immersed in the water so that the height of the water in the cylinder rises by 4 cm. If the radius of one ball is half of the other and the diameter of the cylinder is 18 cm, then the radii of the spherical balls are
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Correct answer: C
Explanation
The correct answer is option 3
r2 = 2r1
R = 18/2 = 9 cm
Volume of cylinder = Vol. of two spheres
πR2h = 4/3 π(r13 + r23)
π × 92 × 4 = 4/3 π[r13 + (2r1)3]
92 × 4 = 4/3 × 9r13
r13 = 27
r1 = 3
r2 = 6