Hypothesis tests for a population mean with standard deviation known Use the information below to answer all questions:
At a large company, the attitudes of workers are'regularly measured with a standard test. The scores on the test are from 0 to 100 with higher score indicating greater satisfaction. The mean score over all company's employees was 74, with a standard deviation of 8. Some time ago, the company adopted the policy that workers could spend one day per week working form home. After the policy had been in place for some time, a random sample of 80 workers was given the test. The sample mean was 76. Assume that the standard deviation is still 8. Can we conclude that the mean level of satisfaction is different since the policy change at the alpha = 0.05 level?