Q26 of 162 Page 1

Mark the correct alternative in the following:

Suppose A1, A2,...,A30 are thirty sets each having 5 elements and B1, B2,...,Bn are n sets each with 3 elements, let and each element of S belongs to exactly 10 of the and exactly 9 of the , then n is equal to


If elements are not repeated then number of elements in A1⋃A2⋃A3⋃….⋃A30=30*5=150


But, each element of S is in 10 of



If elements are not repeated then number of elements in B1⋃B2⋃B3⋃….⋃Bn=3*n


But, each element of S is in of




∴3× n=15× 9


∴n=45

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