Use the calculator to determine the confidence intervals for the following.
Exercise 1
A random sample of 49 shoppers showed that they spend an average of $23.45 per visit at Barnes and Nobles Book store. The standard deviation of the population is $2.80. Find the 90% confidence interval of the true mean.
Exercise 2
The daily salaries of substitute teachers for 8 local school districts are shown below. Find the 95% confidence interval for the mean of the salaries.
$60 $56 $60 $55 $70 $55 $60 $55
Exercise 3
An employment counselor found that in a sample of 100 unemployed workers, 65% were not interested in returning to work. Find the 95% confidence interval of the true proportion of workers who do not wish to return to work.
Use the p-value method and your calculator to test the following hypotheses. Make sure to show all steps of the procedure.
Exercise 4
A park manager suggests that the average attendance for the 10 most popular national parks last year was 6 million. The number of visits for the 10 most popular parks this year is shown below. At α = 0.01, has the average attendance changed? The data are in millions of people.
4.7 17.2 14.0 6.1 6.1 4.9 9.3 9.4 6.4 6.1
Exercise 5
A poll done for Newsweek found that 13% of Americans have seen or sensed the presence of an angel. A contingent doubts that the percent is really that high. It conducts its own survey. Out of 76 Americans surveyed, only two had seen or sensed the presence of an angel. As a result of the contingent’s survey, would you agree with the Newsweek poll? Use a 1% percent level of significance to test the claim of the contigent.
Exercise 1
A random sample of 49 shoppers showed that they spend an average of $23.45 per visit at Barnes and Nobles Book store. The standard deviation of the population is $2.80. Find the 90% confidence interval of the true mean.
Exercise 2
The daily salaries of substitute teachers for 8 local school districts are shown below. Find the 95% confidence interval for the mean of the salaries.
$60 $56 $60 $55 $70 $55 $60 $55
Exercise 3
An employment counselor found that in a sample of 100 unemployed workers, 65% were not interested in returning to work. Find the 95% confidence interval of the true proportion of workers who do not wish to return to work.
Use the p-value method and your calculator to test the following hypotheses. Make sure to show all steps of the procedure.
Exercise 4
A park manager suggests that the average attendance for the 10 most popular national parks last year was 6 million. The number of visits for the 10 most popular parks this year is shown below. At α = 0.01, has the average attendance changed? The data are in millions of people.
4.7 17.2 14.0 6.1 6.1 4.9 9.3 9.4 6.4 6.1
Exercise 5
A poll done for Newsweek found that 13% of Americans have seen or sensed the presence of an angel. A contingent doubts that the percent is really that high. It conducts its own survey. Out of 76 Americans surveyed, only two had seen or sensed the presence of an angel. As a result of the contingent’s survey, would you agree with the Newsweek poll? Use a 1% percent level of significance to test the claim of the contigent.