1. Suppose a company fleet of 20 cars contains 7
cars that do not meet government exhaust
emissions standards and are therefore
releasing excessive pollution. Moreover,
suppose that a traffic policeman randomly
inspects 5 cars. What is the probability that he
will find 2 cars that exceed pollution control
standards?
2. From a group of 7 democrats and 12
republicans, a committee of 4 is selected at
random. What is the probability that the
committee consists of 2 democrats and 2
republicans.
3. Suppose that in a set of 20 accounts 6 contain
errors. If an auditor samples 4 to inspect, what is
the probability that:
(a) No errors are found?
(b) 4 errors are found?
(c) No more than 2 errors are found?
(d) At least 3 errors are found?
4. A football team has 22 players for offense and
25 players for defense and kicking. If four
team captains are chosen randomly, what is
the probability that three of the captains will
be from the offense?
Answers
1. 0.3874
2. 0.357
3. (a) No errors are found? 0.2066
(b) 4 errors are found? 0.0031
(c) No more than 2 errors are found? 0.939
(d) At least 3 errors are found? 0.0611
4. ANS: 0.2158