Q11. The accounts of a corporation show that, on average, accounts payable are $125.32. An auditor checked a random sample of 16 of these accounts . The sample mean was $131.78 and the sample standard deviation was $25.41 . Test at a 5% significance level against a two sided alternative that the corporation's accounts are accurate. Assume a normally distributed population Q12. Fueleconomy.gov, the official US government source for fuel economy information, allows users to share gas mileage information on their vehicles . The histogram below shows the distribution of gas mileage in miles per gallon (MPG) from 14 users who drive a 2012 Toyota Prius. The sample mean is 53.3 MPG and the sample standard deviation is 5.2 MPG. 55 Mileage (in MPG) We would like to use these data to evaluate the average gas mileage ofal/ 2012 Prius b. drivers. Do you think this is reasonable? Why or why not? The Environmental Protection Agency (EPA ) claims that a 2012 Prius gets 50 MPG (city and highway mileage combined). Does the information in this sample of 14 observations provide strong evidence against this claim for drivers who participate on C. fueleconomy .gov ? Assume a normally distributed population. Calculate a 95% confidence interval for the average gas mileage of 2012 Prius drivers who d. participate on fueleconomy .gov . Calculate a 99% confidence interval for the average gas mileage of 2012 Prius drivers who participate on fueleconomy .gov . Q13. Among a random sample of 331 American adults who do not have a 4-year university degree and who are not currently enrolled in school , 48 % said they decided not to go to university because they could not afford it. Citing this point estimate, a newspaper article states that only a minority of the Americans who decide not to go to university do so because they cannot afford it. Conduct a hypothesis test to determine if this survey provides evidence supporting this statement using a 5% significance level. Q14. A random sample of 802 supermarket shoppers determined that 376 shoppers preferred generic-brand items. A researcher tests the null hypothesis that at least one -half of all shoppers prefer generic-brand items against the alternative hypothesis that the population proportion is less than one -half . Find the Type II error probability and the power of a 10% - level test if, in fact, 45% of the supermarket shoppers preferred generic brands. * Pew Research Center Publications , Is College Worth It? Data collected between March 15-29, 2011