1.

24 people likes apple, 18 people likes orange, 5 likes both apple and orange, and rest of the people likes only grapes. If total 50 people are present how many how many like only grapes?1. 152. 113. 174. 13

Answer» Correct Answer - Option 4 : 13

Concept: 

Set theory:

  • A ∪ B means set of all the values in the set A and B.
  • ∩ B is the set of common elements of A and B.
  • Subset (⊂) is the set such that all the elements of the subset are in the set from which the subset is taken from.
  • Number of elements in set A = n(A)
  • n(A∪B) = n(A) + n(B) - n(A∩B) = n(A) + n(B - A) = n(B) + n(A - B)
  • A' = U - A, where U is a universal set given and A is any set
  • n(A') = n(U) - n(A)
  • A - B = set values of set A not in set B
  • n(A - B) = n(A) - n(A∩B)

 

Calculation:

Let Set A of people who like apples and Set B of people who like orange and U is set of all people

Given n(A) = 24, n(B) = 18 and n(U) = 50

Also given n(A ∩ B) = 5

n(A ∪ B) = n(A) + n(B) - n(A ∩ B)

⇒ n(A ∪ B) = 24 +18 - 5 

⇒ n(A ∪ B) = 37 

Now, if Set C is of people who likes only grapes

n(C) = n(U) - n(A ∪ B)

n(C) = 50 - 37 = 13

∴ People who likes only grapes n(C) = 13



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