"For John Only "
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"For John Only "...
"For John Only "
I noticed you have answered similiar questions to the ones I would like for you to help me with. Hopefully you will be able to.
1. The commissioner of the state police is reported as saying that about 10% of reported auto thefts involve
owners whose cars haven't really been stolen. What null and alternative hypotheses would be appropriate in
evaluating this statement made by the commissioner?
A. H0: p ≤ 0.10 and H1: p > 0.10
B. H0: p ≥ 0.10 and H1: p 0.10 and H1: p ≤ 0.10
2. Because of the popularity of movies as an entertainment medium for adolescents, an entrepreneur plans
to do a national study of the average cost of a movie ticket. If you assume that s = $0.50, what sample size
would the entrepreneur have to take to be 95% confident that the estimate was within $0.25 of the true
mean ticket prices?
3. In sampling without replacement from a population of 900, it's found that the standard error of the
mean, , is only two-thirds as large as it would have been if the population were infinite in size. What is
the approximate sample size?
4. To schedule appointments better, the office manager for an ophthalmologist wants to estimate the
average time that the doctor spends with each patient. A random sample of 49 is taken, and the sample
mean is 20.3 minutes. Assume that the office manager knows from past experience that the standard
deviation is 14 minutes. She finds that a 95% confidence interval is between 18.3 and 22.3 minutes. What
is the point estimate of the population mean, and what is the confidence coefficient?
A. 20.3, 0.95
B. 18.3, 95%
C. 18.3, 0.95
5. Which of the following statements correctly compares the t-statistic to the z-score when creating a
A. Using t is easier because you do not have to worry about the degrees of freedom, as you do with z.
B. Use t when the sample size is small, and the resulting confidence interval will be narrower.
C. The value of z relates to a normal distribution, while the value of t relates to a Poisson distribution.
D. You can use t all the time, but for n ≥ 30 there is no need, because the results are almost identical if you use t or z.
6. What sample size is required from a very large population to estimate a population proportion within
0.05 with 95% confidence? Don't assume any particular value for p.
7. Consider a null hypothesis stating that the population mean is equal to 52, with the research hypothesis
that the population mean is not equal to 52. Assume we have collected 38 sample data from which we
computed a sample mean of 53.67 and a sample standard deviation of 3.84. Further assume the sample
data appear approximately normal. What is the p-value you would report for this test?
8. Which of the following statements about p-value testing is true?
A. The p-value is the lowest significance level at which you should reject H0.
B. P-value testing applies only to one-tail tests.
C. The p represents sample proportion.
D. P-value testing uses a predetermined level of significance.
9. If the level of significance (α) is 0.005 in a two-tail test, how large is the nonrejection region under the
curve of the t distribution?
10. When the confidence coefficient is large, which of the following is true?
A. It's more likely that the test will lead you to reject the null hypothesis.
B. Its value is close to 1.0, but not larger than 1.0.
C. Its value is 1.0 or larger.
D. The confidence interval is narrow.
11. Which of the following statements about
11. Which of the following statements about hypothesis testing is false?
A. The rejection region is always given in units of standard deviations from the mean.
B. In both the one-tailed and two-tailed tests, the rejection region is one contiguous interval on the number line.
C. A Type I error is the chance that the researcher rejects the null hypothesis when in fact the null hypothesis is true.
D. The test will never confirm the null hypothesis, only fail to reject the null hypothesis.
12. In a simple random sample from a population of several hundred that's approximately normally
distributed, the following data values were collected.
68, 79, 70, 98, 74, 79, 50, 102, 92, 96
Based on this information, the confidence level would be 90% that the population mean is somewhere
A. 73.36 and 88.24.
B. 65.33 and 95.33.
C. 69.15 and 92.45.
D. 71.36 and 90.24.
13. What is the rejection region for a two-tailed test when α = 0.05?
A. |z | > 2.575
B. z > 2.575
C. |z | > 1.645
D. |z | > 1.96
14. H0 is p = 0.45 and H1 is p ≠ 0.45. What type of test will be performed?
A. Two-tail testing of a mean
B. One-tail testing of a mean
C. Two-tail testing of a proportion
D. One-tail testing of a proportion
15. A portfolio manager was analyzing the price-earnings ratio for this year's performance. His boss said
that the average price-earnings ratio was 20 for the many stocks that his firm had traded, but the portfolio
manager felt that the figure was too high. He randomly selected a sample of 50 price-earnings ratios and
found a mean of 18.17 and a standard deviation of 4.60. Assume that the population is normally
distributed, and test at the 0.01 level of significance. Which of the following is the correct decision rule for
the manager to use in this situation?
A. If z > 2.33, reject H0.
B. Because –2.81 falls in the rejection region, reject H0. At the 0.01 level, the sample data suggest that the average priceearnings
ratio for the stocks is less than 20.
C. Because 2.81 is greater than 2.33, reject H0. At the 0.01 level, the sample data suggest that the average price-earnings ratio
for the stocks is less than 20.
D. If t > 2.68 or if t < –2.68, reject H0.
16. A federal auditor for nationally chartered banks, from a random sample of 100 accounts, found that the
average demand deposit balance at the First National Bank of Arkansas was $549.82. If the auditor needed
a point estimate for the population mean for all accounts at this bank, what should he use?
A. There's no acceptable value available.
B. The average of $54.98 for this sample
C. The auditor should survey the total of all accounts and determine the mean.
D. The average of $549.82 for this sample
17. A researcher wants to carry out a hypothesis test involving the mean for a sample of n = 20. While the
true value of the population standard deviation is unknown, the researcher is reasonably sure that the
population is normally distributed. Given this information, which of the following statements would be
A. The researcher should use the z-test because the population is assumed to be normally distributed.
B. The t-test should be used because the sample size is small.
C. The t-test should be used because α and μ are unknown.
D. The researcher should use the z-test because the sample size is less than 30.
18. A human resources manager wants to determine a confidence interval estimate for the mean test score
for the next office-skills test to be given to a group of job applicants. In the past, the test scores have been
normally distributed with a mean of 74.2 and a standard deviation of 30.9. Determine a 95% confidence
interval estimate if there are 30 applicants in the group.
A. 64.92 to 83.48
B. 13.64 to 134.76
C. 68.72 to 79.68
D. 63.14 to 85.26
19. A random sample of 10 employees is selected from a large firm. For the 10 employees, the number of
days each was absent during the past month was found to be 0, 2, 4, 2, 5, 1, 7, 3, 2, and 4. Of the
following values, which would you use as the point estimate for the average number of days absent for all
the firm's employees?
20. The Coca-Cola Company has 40% of the cola market. Determine the probability that a sample
proportion for n = 30 is within 0.10 of the true population proportion of 0.40, which represents the
proportion of cola drinkers who prefer a Coca-Cola drink.