1. Suppose a population has a mean of 400 and a standard deviation of 24. If a random sample of size 144 is drawn from the population, the probability of drawing a sample with a mean less than 402 is _______.
·
0.8413
·
0.1587
·
0.9875
·
0.6826
·
0.3413
2. The empirical rule says that approximately what percentage of the values would be within 2 standard deviations of the mean in a bell shaped set of data?
·
95%
·
68%
·
97.7%
·
100%
·
50%
3. A large industrial firm allows a discount on any invoice that is paid within 30 days. Of all invoices, 10% receive the discount. In a company audit, 10 invoices are sampled at random. The probability that fewer than 3 of the 10 sampled invoices receive the discount is approximately_______________.
·
0.057
·
0.9298
·
0.3486
·
0.1937
·
0.001
4. James Desreumaux, VP of Human Resources of American First Banks (AFB), is reviewing the employee training programs of AFB banks. His staff randomly selected personnel files for 100 tellers in the Southeast Region and determined that their mean training time was 25 hours. Assume that the population standard deviation is 5 hours. The 95% confidence interval for the population mean of training times is ________.
·
24.02 to 25.98
·
23.32 to 35.46
·
15.20 to 34.80
·
16.78 to 33.23
·
24.18 to 25.82
5. A market research team compiled the following discrete probability distribution on the number of sodas the average adult drinks each day. In this distribution, x represents the number of sodas which an adult drinks.
| x | P(x) |
| 0 | 0.30 |
| 1 | 0.10 |
| 2 | 0.50 |
| 3 | 0.10 |
The mean (average) value of x is _______________.
·
1.4
·
2.55
·
1.75
·
3.02
·
2.10
6. A large national company is considering negotiating cellular phone rates for its employees. The Human Resource department would like to estimate the proportion of its employee population who own an Apple iPhone. A random sample of size 250 is taken and 40% of the sample own and iPhone.. The 95% confidence interval to estimate the population proportion is _______.
·
0.35 to 0.45
·
0.37 to 0.43
·
0.34 to 0.46
·
0.40 to 0.42
·
0.39 to 0.41
7. If x is a binomial random variable with n=10 and p=0.8, what is the probability that x is equal to 4?
·
.0055
·
.0063
·
.232
·
.994
·
.124
8. The mean life of a particular brand of light bulb is 1200 hours and the standard deviation is 75 hours. Tests show that the life of the bulb is approximately normally distributed. It can be concluded that approximately 68% of the bulbs will last between _______.
·
1050 and 1350 hours
·
900 and 1100 hours
·
1125 and 1275 hours
·
950 and 1050 hours
·
975 and 1475 hours
9. The normal distribution is used to test about a population mean for large samples if the population standard deviation is known. "Large" is usually defined as _______.
·
at least 100
·
at least 5% of the population size
·
at least 10
·
at least 30
·
at least 12
10. Completion time (from start to finish) of a building remodeling project is normally distributed with a mean of 200 work-days and a standard deviation of 10 work-days. To be 99% sure that we will not be late in completing the project, we should request a completion time of _______ work-days.
·
250
·
207
·
200
·
223
·
211
11. The expected (mean) life of a particular type of light bulb is 1,000 hours with a standard deviation of 50 hours. The life of this bulb is normally distributed. What is the probability that a randomly selected bulb would last fewer than 940 hours?
·
0.1151
·
0.3849
·
0.6563
·
0.8849
·
0.6151
12. Life tests performed on a sample of 13 batteries of a new model indicated: (1) an average life of 75 months, and (2) a standard deviation of 5 months. Other battery models, produced by similar processes, have normally distributed life spans. The 98% confidence interval for the population mean life of the new model is _________.
·
71.77 to 78.23
·
79.86 to 81.28
·
61.60 to 88.41
·
63.37 to 86.63
·
71.28 to 78.72
13. Elwin Osbourne, CIO at GFS, Inc., is studying employee use of GFS e-mail for non-business communications. He plans to use a 95% confidence interval estimate of the proportion of e-mail messages that are non-business; he will accept a 0.05 error. Previous studies indicate that approximately 30% of employee e-mail is not business related. Elwin should sample _______ e-mail messages.
·
457
·
323
·
14
·
100
·
12
14. According to the central limit theorem, for samples of size 64 drawn from a population with µ = 800 and σ = 56, the standard deviation of the sampling distribution of sample means would equal _______.
·
800
·
8
·
7
·
80
·
100
15. Maureen McIlvoy, owner and CEO of a mail order business for wind surfing equipment and supplies, is reviewing the order filling operations at her warehouses. Her goal is 100% of orders shipped within 24 hours. In previous years, neither warehouse has achieved the goal, but the East Coast Warehouse has consistently out-performed the West Coast Warehouse. Her staff randomly selected 200 orders from the West Coast Warehouse (population 1) and 400 orders from the East Coast Warehouse (population 2), and reports that 190 of the West Coast Orders were shipped within 24 hours, and the East Coast Warehouse shipped 372 orders within 24 hours. Maureen's alternative hypothesis is _______.
p1 – p2 > 0
·
m1 - m2 > 0
·
m1 - m2 ≥ 0
·
m1 - m2 ≠0
·
p1 – p2 ≠0
16. According to the central limit theorem, for samples of size 64 drawn from a population with µ = 800 and σ = 56, the mean of the sampling distribution of sample means would equal _______.
·
8
·
100
·
800
·
80
·
7
17. If x is a binomial random variable with n=10 and p=0.8, the mean value of x is _____.
·
8
·
3.2
·
6
·
4.8
·
48
18. Consider the following null and alternative hypotheses.
Ho: m ≤ 67
Ha: m > 67
These hypotheses _______________.
·
are not mutually exclusive
·
indicate a one-tailed test with a rejection area in the left tail
·
indicate a one-tailed test with a rejection area in the right tail
·
indicate a two-tailed test
·
19. A researcher wants to determine the sample size necessary to adequately conduct a study to estimate the population mean to within 5 points. The range of population values is 80 and the researcher plans to use a 90% level of confidence. The sample size should be at least _______.
·
44
·
700
·
692
·
216
·
62
Medical Wonders is a specialized interior design company focused on healing artwork. The CEO, Kathleen Kelledy claims that artwork has healing effects for patients staying in a hospital, as measured by reduced length of stay. Her current client is a children's cancer hospital. Kathleen is interested in determining the effect of three different pieces of healing artwork on children. She chooses three paintings (a horse photo, a bright abstract, and a muted beach scene) and randomly assigns six hospital rooms to each painting. Kathleen's null hypothesis is _____________.
·
m 1 ≤ m 2 ≥ m 3
·
m 1 ≤ m 2 ≤ m 3
·
m 1 ≠ m 2 ≠ m 3
·
m 1 ≥ m 2 ≥ m 3
·
m 1 = m 2 = m 3
