1.The value of z (or t ) that establishes the boundary of the rejection region i
ID: 3258670 • Letter: 1
Question
1.The value of z (or t) that establishes the boundary of the rejection region in hypothesis testing is called the critical value for the test.
T F
2. When the p-value is used for hypothesis testing, the null hypothesis is rejected when the p-value > a.
T F
3. Independent simple random samples are taken to test the difference between the means of two populations. The sample sizes are n1 = 32 and n2 = 40. The sampling distribution of the difference between the sample means is a t distribution with 72 degrees of freedom.
T F
4. Which of the following is NOT a step of hypothesis testing:
a. state the null and alternative hypothesis
b. choose a test statistic and a significance level for the test
c. calculate alpha, select the p-value, and compare the
d. compute the value of the test statistic from your sample data
e. apply the appropriate decision rule and make your decision
5. Which of the following statements about the sampling distribution of the sample proportion is TRUE:
a. it is approximately normal, so long as np > 5 and n(1 - p) > 5
b. it is centered on the population proportion p
c. it has standard deviation equal to the square root of p(1-p)/n.
d. b and c only
e. all of the above
6. A severe tornado recently touched down in Bryce County, Kansas. Government policy calls for emergency support if the average damage done to the population of all farms in the county exceeds $20,000. At the moment, the government is not at all convinced that this criterion has been met. To demonstrate that the average damage is more than the $20,000 figure, you audit a simple random sample of 40 farms in the county and find that the average damage for the farms in the sample is $21,100. Should this be considered sufficient sample evidence to convince a reluctant government agency to provide the emergency support? Use a significance level of 5%. Assume the population standard deviation is $3,700. (Perform all steps of hypothesis testing, including the p-value.)
7. Last year, 45% of the players using online game site ABCya.com were from outside the U.S. The site conducted a survey of 200 randomly selected online customers in an effort to determine whether that percentage has changed. Suppose that 98 of players were from outside the U.S. The company wants you to set up an appropriate two-tailed hypothesis test. Use a significance level of 5%. What do you conclude? (Perform all steps of hypothesis testing, including the p-value.)
8. A study conducted at the University of Chicago Hospitals compared the hospital-related performance of “hospitalists”—physicians specializing in caring for hospitalized patients—to the performance of general internists who devote only a small percentage of their time caring for hospitalized patients. One of the variables examined was the average time that patients under the care of each of these two classes of physicians spent in the hospital. Patients in the sample who were cared for by internists stayed for an average of 4.59 days with a standard deviation of 1.8 days, while patients in the sample who were cared for by hospitalists left after an average stay of 4.1 days with a standard deviation of 1.3 days. The sample included 10 patients who were cared for by internists and 15 patients who were cared for by hospitalists. Construct a hypothesis test to test the null hypothesis that there would be no difference in the average hospital stay for the two populations represented here. Assume that the population distributions are normal and have equal standard deviations. Use a significance level of 1%. What is your conclusion? (Perform all steps of hypothesis testing, including the p-value.)
Explanation / Answer
1 .true
2. false
when p> a failed to reject null hypothesis
4.
c. calculate alpha, select the p-value, and compare the
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