Question 15 A study of 40 English composition professors showed that they spent, on average, 12 minutes correcting al student's term paper. The population standard deviation was 2 min. a. Find and the 90% confidence interval for the mean grading time of all composition papers. b. intrepret the meaning of the confidence interval you found in part a. b. Does the confidence interval, at 90% confidence level, provide sufficient evidence that the mean time English composition professors spend on grading term papers exceeds 11 minutes? Write an appropriate inequality to justify your answer.