A cylinder is 6 cms in diameter and 6 cms in height. If spheres of the same size are made from the material obtained, what is the diameter of each sphere?  Choices
A) 5 cms
B) 2 cms
C) 3 cms
D) 4 cms
E) 6 cms

Rationale: since the sphere is made out of the cylinder material their volume will be same volume of cylinder = pi * 3 ^ 2 * 6 volume of one sphere = 4 / 3 * pi * r ^ 3 ( where r is radius of sphere ) so if there are n such sphere ' s equating the volumes , pi * r ^ 2 * h = n * ( 4 / 3 ) * pi * r ^ 3 n is the number of spheres , substituting the , r and h 9 * 6 = n * ( 4 / 3 ) * ( d / 2 ) ^ 3 d is the diameter of a sphere , n = ( 9 * 6 * 3 * 8 ) / ( 4 * d ^ 3 ) n = 324 / d ^ 3 now substitute the given answers for d and find the values for n , since a n has to be an integer only value fit for d is 3 , answer : c
Answer: C