UPSC NDA Math Model Paper 9

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) = 1