The police chief of a large city claims that the mean age of bicycle thieves is 10.5 years. A sociologist who feels that this figure is too high takes a random sample of 28 cases of bicycle theft from the police chief's files, getting a mean of 8.9 years and a standard deviation of 3.2 years. Test the sociologist's hunch at the .01 significance level.
Ho: The mean age of bicycle thieves is 10.5 years
Ha: The mean age of bicycle ...