In a family of 10 members, 7 of them like tea or coffee, 4 of them like tea and 5 of them like coffee. How many of them like only coffee?

Correct Answer: 3
We know, n (T ∪ C) = n (T) + n (C) – n (T ∩ C) Given, n (T ∪ C) = 7, n(T)=4, n(C)=5 7=4+5- n (T ∩ C) n (T ∩ C) = 2. n (only C) = n (C ∩ T’) = n (C) – n (T ∩ C) = 5-2=3. 3 members like only coffee.