70 have read magazines A,B and C
100 have read both magazines A and B
80 have read both magazines A and C
90 have read both magazines B and C
150 have read magazines A
170 have read magazines B
160 have read magazines C
(a)(i) how many pupils have read at least one of the magazines?
更新1:
of the 400 pupils in a school, 70 have read magazines A,B and C 100 have read both magazines A and B 80 have read both magazines A and C 90 have read both magazines B and C 150 have read magazines A 170 have read magazines B 160 have read magazines C
更新2:
(a)(ii) how many pupils have read exactly two of the magazines? (a)(iii) how many pupils have read exactly one of the magazines?
更新3:
(b) if one of these 400 pupils is chosen at random, what is the probability that he has not read any of the 3 magazines?
