Chapter 9 Homework 1. Boston's welfare department has stated that the average annual per capita income for a particularly depressed section of the city is $4,800, and the population standard deviation is $900. A citizen's group has sampled 40 families from that section and found the average per capita income to be $4,500. At a 5% level of significance, would you accept or reject the welfare department's figures? a. What type of hypothesis test is this (two-tailed, lower or upper tail)? State null and alternative hypotheses. b. Use the level of significance () to determine the \"critical value\" (cut-off point), draw on a distribution c. What does the level of significance mean in this problem? d. Compute the test statistic e. Make a decision: Accept or Reject Ho f. Interpret your decision 2. An Omaha electronics firm has received a shipment of 200 special components designed to maintain a constant power output, 64 watts, with a standard deviation of 4 watts. A sample of 36 of these components produced an average of 64.8 watts. The firm in interested in knowing, at the .02 significance level, if the manufacturer's claim of 64 watts is true. a. What type of hypothesis test is this (two-tailed, lower or upper tail)? State null and alternative hypotheses. b. Use the level of significance () to determine the \"critical value\" (cut-off point), draw on a distribution c. What does the level of significance mean in this problem? d. Compute the test statistic e. Make a decision: Accept or Reject Ho f. Interpret your decision 3. For the domestic airline industry the amount of time each plane must spend in maintenance is a critical factor. The records show that for a sample of 49 planes, Central Airways average downtime is 12 hours. The industry average is 11 hours, and the standard deviation is 3.5 hours. At a significance level of .10, should the company conclude that its downtime differs significantly from the industry average? a. What type of hypothesis test is this (two-tailed, lower or upper tail)? State null and alternative hypotheses. b. Use the level of significance () to determine the \"critical value\" (cut-off point), draw on a distribution c. What does the level of significance mean in this problem? d. Compute the test statistic e. Make a decision: Accept or Reject Ho f. Interpret your decision