Q. 15 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.
n(H) = 25
n(T) = 26
n(I) = 26
n(H I) = 9
n( T I ) = 8
n( H T ) = 11
n(H T I ) = 3
the number of people who read at least one of the newspapers = n(HTI) = n(H) + n(T) + n(I) - n(H I) - n( T I ) - n( H T ) + n(H T I )
= 25 + 26 + 26 - 9 - 8 - 11 + 3
= 52
Hence, 52 people who read at least one of the newspapers.
(ii) number of people who read exactly one newspaper =
the number of people who read at least one of the newspapers - n(H I) - n( T I ) - n( H T ) + 2 n(H T I )
= 52 - 9- 8 -11 + 6
= 30
Hence, 30 number of people who read exactly one newspaper .