question_answer

A cylindrical tub of radius 12 cm contains water to a depth of 20 cm. A spherical iron ball is dropped into the tub and thus the level of the water is raised by 6.75 cm. What is the radius of the sphere?

A)  9 cm                           

B)  13 cm 

C)  11 cm             

D)         15 cm 

Correct Answer: A

Solution :

Radius of the cylindrical tub (r) = 12 cm. Height of water level in the tub (h) = 20 cm. When the Spherion iron ball is dropped into the tub, the level of water rises by 6.75 cm. Volume increased in the cylindrical part Thus, the volume of the spherical ball Let R be the radius of the spherical ball. Volume of spherical ball Now, R = 9 Hence, the radius of the sphere = 9 cm.