Practice Test
Chapter 6 part 1
A Zillion PointsName______
For Questions 1-3, Consider that a police study of 250 accidents found that 72% of the drivers involved were impaired in some way. Find
1. the mean of the distribution
2. the standard deviation of the distribution
3. the probability of between 103 and 156 impaired drivers
4. A customer service center has a probability of 48% of answering a phone call on any given ring. If a call gets transferred to an answering machine after the fifth ring, how many of the 2650 daily calls are transferred to an answering machine?
5. A fair coin is flipped 12 times. Find the probability of getting between 4 and 10 heads.
6. The percentage of American men who say they would marry the same women over again is 80%. The percentage of American woman who say they would marry the same man over again is 50%.
a) Given a group of 14 American men, what is the probability at least half would marry the same woman again? What is the probability less than four would marry the same woman again?
b) Given a group of 19 American women, what is the probability more than 13 would marry the same man again? What is the probability that between 9 and 15 would marry the same man again?
7. A customer service center has a probability of 53% of answering a phone call on any given ring. If a call gets transferred to an answering machine on the fifth ring, what percentage of the 2650 daily calls are transferred to an answering machine?
8. A manufacturer of micro switches has a defect rate of 8%. A company randomly selects samples of size 12 to test for defects. Find the probability of
a) exactly 4 bad switches
b) no more than 5 bad switches
c) 8 or less bad switches
d) no bad switches
9. Twenty percent of the cows in MercerCounty have green ear tags. If we sample 100 randomly selected cows, find the following.
A. The average number of cows with green ear tags.
B. The standard deviation.
C. The probability that 92 of the cows have green ear tags.
10. A home security system is designed to have a 99% reliability rate. Suppose that nine homes equipped with this system experience an attempted burglary. Find the probabilities of these events:
A. At least one of the alarms is triggered.
B. More than seven of the alarms are triggered.
C. Eight or fewer alarms are triggered.
11. Sketch a scatter plot and the regression line for the following Data. Find the coefficient of determination, the correlation coefficient, and sketch a residual plot. Find the points with the highest and lowest residuals. Are any of the x’s or y’s outliers? Explain.
x / 2 / 5 / 8 / 11 / 19 / 27 / 31 / 40 / 63y / .12 / .3 / .24 / .29 / .54 / .64 / .58 / 1.2 / 1.55
12. For questions a-f, suppose 2 fair dice are rolled. Give the probability of each event
a. The sum is a prime number.b. At least one die is a five.
c. The product of the numbers is nine.
d. The difference of the numbers is seven.
e. Neither die is a two
f. The dies show the same number
13. A survey indicated that 3 out of every 5 people support the President’s tax cuts. If 10 people are chosen atrandom, find the probability that
a) exactly half support the president
b) 9 or more support the president
14. A multiple choice test has twenty questions. Each question has choices A through E. If a student randomly guesses at the answers to the questions, find the probability that the student will get:
A. Exactly seven answers correct.
B. At least three and less than nine correct.
C. Between two and fourteen correct, including two and fourteen.
D. At least 5 correct.
15. If the expected value of successes in a binomial experiment of 70 trials is 42, the standard deviation of the number of successes is approximately:
a) 4.58
b) 4.09
c) 5.86
d) 3.83
16. The following is a demographic breakdown of the students at SharpsvilleHigh School
Freshman / Sophomores / Juniors / Seniors35% / 30% / 20% / 15%
Find the probability that in a randomly selected group of sixteen students
A. At least 7 are freshman.
B. No more than 10 are seniors
C. At least half are either Juniors or Seniors
D. No more than 2 are freshman
E. At least 4 are Sophomores
F. There are exactly 7 Freshman
17. The following summary statistics were found for a data set: (12 points)
r=-.8124
- Find the slope of the regression line
- Find the y intercept of the regression line
- Find the correlation coefficient
- Find the coefficient of determination
- Find the regression line equation
- Find a point on the line