Find People Who Read Newspapers H, T and I
Question:
In a survey of 60 people, it was found that 25 people read newspaper H, 26 read newspaper T, 26 read newspaper I, 9 read both H and I, 11 read both H and T, 8 read both T and I, 3 read all three newspapers. Find:
(i) the number of people who read at least one of the newspapers.
(ii) the number of people who read exactly one newspaper.
Solution
(i)
\[ n(H\cup T\cup I) \] \[ =25+26+26-11-9-8+3 \] \[ =52 \]Hence, 52 people read at least one newspaper.
(ii)
\[ \text{Only H}=25-11-9+3=8 \] \[ \text{Only T}=26-11-8+3=10 \] \[ \text{Only I}=26-9-8+3=12 \] \[ \text{Exactly one newspaper}=8+10+12 \] \[ =30 \]Hence, 30 people read exactly one newspaper.