Statistics review problems in preparation for tomorrow's test.

1. The probability that a motorist will use a credit card for gas purchases at
a large service station on the Trans Canada Highway is 7/8. If eight cars
pull up to the gas pumps, what is the probability that:
(a) seven of them will use a credit card?
(b) four of them will use a credit card?

2. The probability that a motorist will use a credit card for gas purchases at
a large service station on the Trans Canada Highway is 7/8. If eight cars
pull up to the gas pumps, what is the probability that:
(a) seven of them will use a credit card?
(b) four of them will use a credit card?

3. The probability that a motorist will use a credit card for gas purchases at
a large service station on the Trans Canada Highway is 7/8. If eight cars
pull up to the gas pumps, what is the probability that:
(b) four of them will use a credit card?

4. The manager of the Jean Shop knows that 3 percent of all jeans sold
will be defective, and the money paid for these pairs of jeans will be
refunded. The manager went on holidays for a period of time, and an
employee sold 247 pairs of jeans. The employee reported that refunds
were given for 14 pairs of jeans.
(a) What is the probability that 14 pairs of jeans were defective?
(b) Does the employer have reason to be suspicious of the employee?
(c) Does the employer have proof that the employee did something
wrong?

5. Mary Reed recently entered college and has not decided on a major.
She decides to take an aptitude test in order to help her select a major.
Her results, as well as the results of the other candidates, are as follows:
Talent Mean Standard Deviation Mary Reed's Score z-score
Writing 58 3.7 46
Acting 84 7.9 85
Medicine 37 2.8 44
Law 49 4.7 41
(a) Rewrite each of Mary Reed's scores as z-scores.
(c) In which area does
(b) In which area does
she have the least talent?
she have the most talent?

6. Vancouver Halifax
Two consumer groups, one in
Cereal Brand Rating Cereal Brand Rating
Vancouver and one in
A 1 P 25
Halifax, recently tested five
B 10 Q 35
brands of breakfast cereal for
C 15 R 45
taste appeal. Each consumer
D 21 S 50
group used a different rating
E 28 T 70
system.
Which cereal has the higher "taste appeal" rating?

7. Numerous packages of raisins were weighed. The mean mass was 1600
grams, and the standard deviation was 40 grams. Trudy bought a package that
had a z-score of -1.6. What was the mass of Trudy's package of raisins?