Review Exercises for Midterm Exam 2

1. At a swimwear store, the managers found that 16 women bought white bathing suits, 4 bought red suits, 3 bought blue suits and 7 bought yellow suits. If a customer is selected at random, find the probability that she bought

(a) A blue suit.

(b) A yellow or a red suit.

(c) A white or a yellow or a blue suit.

(d) A suit that was not red.

2. A Gallup Poll found that 78% of Americans worry about the quality and healthfulness of their diet. If 5 people are selected at random, find the probability that

(a) all 5 worry about the quality and healthfulness of their diet.

(b) at least one person worry about the quality and healthfulness of his diet.

3. The Probability that a customer will buy a television set and buy an extended warranty is 0.03. If the probability that a customer will purchase a television set is 0.11, find the probability that the customer will also purchase the extended warranty.

4. At a large factory, the employees were surveyed and classified according to their level of education and whether they smoked.

(a) Fill in the blanks in the table above.

(b) Find the probability of a randomly selected employee who is a high school graduate.

(c) Find the probability of a randomly selected employee who is a high school graduate or do not smoke.

(d) Find the probability of a randomly selected employee who is a high school graduate and do not smoke.

(e) Find the probability of a randomly selected employee who is a high school graduate given that he does not smoke.

5. How many different arrangements of the letters in the word bread can be made?

6. How many different computer passwords are possible if each consists of 4 symbols and if the first one must be a letter and the other 3 must be digits?

7. There are 12 students who wish to enroll in a particular course. There are only 4 seats left in the classroom. How many different ways can 4 students be selected to attend the class?

8. A bank has a drive-through service. The number of customers arriving during a 15-minute period is distributed as shown. Find the mean, variance, and standard deviation for the distribution.

9. If 60% of all women are employed outside the home, find the probability that in a sample of 20 women,

(a) Exactly 15 are employed.

(b) At least 10 are employed.

(c) At most five are not employed outside the home.

(d) Find the mean, variance and standard deviation for the distribution.