An automobile manufacturer recommends oil change 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.
Reject the null hypothesis
Fail to reject the null hypothesis
2. For the past few years the average score on a common final exam in Psychology has been 80. In a sample of 92 students, the mean score on this year's exam was 82 with standard deviation 8.7. Test at 5% level of significance whether the mean score this year's exam is higher than that of previous years.
Fail to reject the null hypothesis
Reject the null hypothesis
Could you explain how you got the answer please and thank you