A. Scores of high school students on a national mathematics exam in Egypt were normally distributed with a mean of 86 and a standard deviation of 4.
1. What is the probability that a randomly selected student will have a score of 80 or higher?
2. If there were 97,680 students with scores higher than 91, how many students took the test?
B. In a study of television viewing habits among married couples, a researcher found that for a popular Saturday night program, 25% of the husbands viewed the program regularly and 30% of the wives viewed the program regularly. The study found that, for couples where the husband watches the program regularly, 80% of the wives also watch regularly. What is the probability that both the husband and the wife watch the program regularly?
What is the probability that both the husband and the wife watch the program regularly?