1. An automobile manufacturer recommends oil change intervals of 3.000 miles. To compare actual intervals to the recommendation, the company randomly samples records of 50 oil changes at service facilities and obtains sample mean 3.752 miles with sample standard deviation 638 miles. Determine whether the data provide sufficient evidence. at the 5% level of significance, that the population mean interval between oil changes exceeds 3.000 miles. 2. The average number of days to complete recovery from a particular type of knee operation is 123.7 days. From his experience a physician suspects that use of a topical pain medication might be lengthening the recovery lime. He randomly selects the records o seven knee surgery patients who used the topical medication. The times to total recovery were: 128, 135, 121, 142, 126, 151, 123 Assuming a normal distribution of recovery times, perform the relevant test of hypotheses at the 10% level of signiticance