Let M , B and L be the set of students studying Mathematics, Business and Literature, respectively. ∴ n (M) = 32, n (B) = 38 , n (L) = 30 n (M ∩ L) = 7 , n (M ∩ B) = 10 , n (B ∩ L) = 8 and n (M ∩ B ∩ L) = 5 Hence, total number of students studying exactly one subject = n (M) + n (B) + n (L) - 2 {n (M ∩ B) + n (B ∩ L) + n (M ∩ L)} + 3n (M ∩ B ∩ l) = 32 + 38 + 30 - 2 (7 + 10 + 8) + 3 (5) = 100 - 50 + 15 = 65