A television station runs a telephone survey to determine how many persons in its primary viewing area have watched three recent special programs, which we call a, b, and c. Of the 1000 persons surveyed, the results are:
221 have seen at least a; 209 have seen at least b; 112 have seen at least c; 197 have seen at least two of the programs; 45 have seen all three; 62 have seen at least a and c; the number having seen at least a and b is twice as large as the number who have seen at least b and c.
- (a) How many have seen at least one special?
- (b) How many have seen only one special program?
Pfeiffer, Applied Probability, 2.3 Problems on Minterm Analysis, exercise 16