Probability Theory Practice
Chapter 4
17. The table shows the results of a survey in which 142 men and 145 women workers ages 25-64 were asked if they have
at least one month’s income set aside for emergencies.
Less than 1 month’s income
1 month’s income or more
Total
Men
66
76
142
Women
83
62
145
Total
149
138
287
a) Find the probability that a randomly selected worker has 1 month’s income or more set aside.
b) Given that a randomly selected worker is a male, find the probability that the worker has less than 1 month’s income.
c) Given that a randomly selected worker has 1 month’s income or more, find the probability that the worker is a female.
d) Are the events of having less than 1 month’s income or more saved and being male independent or dependent? Why?
Principles of Counting
18. There are five finalists in a local pageant. In how many ways may the judges choose a winner and a
runner-up?
19. If the NCAA has applications from 6 universities for hosting its intercollegiate tennis championship in 2013
and 2014, how many ways may they select the hosts for these championships
a) if they are not both to be held at the same university?
b) if they may both be held at the same university?
20. In a primary election, there are four candidates for mayor, five candidates for city treasurer, and two
candidates for county attorney. In how many ways may voters mark their ballots if they vote in all three of the
races?
21. A television director is scheduling a certain sponsor’s commercials for an upcoming broadcast. There are
six slots available for the commercials. In how many ways may the director schedule the commercials
a) if the sponsor has six different commercials, each to be shown once?
b) if the sponsor has two different commercials, each to be shown three times?
22. How many distinct permutations are there of the letters of the word “great”?
23. How many distinct permutations are there of the word “statistics”?
24. Among seven nominees for two vacancies on the city council are three men and four women. In how
many ways may these vacancies be filled
a) with any two nominees?
b) with any two of the women?
c) with one of the men and one of the women?
25. Mr. Jones owns 4 pairs of pants, 7 shirts, and 3 sweaters. In how many ways may he choose 2 of the pairs
of pants, 3 of the shirts, and 1 of the sweaters to pack for a trip?