I need help with answer C

There is concern about the speed of automobiles traveling over a particular stretch of highway. For a random sample of 28 automobiles, radar indicated the following speeds in miles per hour. 58 63 6B 5? 55 72 58 69 53 55 6166 5159 % 54 64 58 5? 6B 61 65 1'1] 63 65 5? 56 61 59 a. Check for evidence of nonnonnality. b. Find a point estimate of the population mean that is unbiased and efcient. c. Use an unbiased estimation procedure to nd a point estimate of the van'ance of the sample mean. a. Is there evidence of nonnonnality? A. Yes, because the normal probability plot of the data is reasonably close to a straight line. . No, because the normal probabiiity plot of the data deviates from a straight line. 5.9.90 No, because the normal probabiiity plot of the data is reasonably close to a straight line. D. Yes, because the normal probability plot of the data deviates from a straight line. b. An unbiased and eicient point estimate of the population mean is 60.75 . (Round to two decimal places as needed.) c. Apoint estimate of the variance of the sample mean is 29.82 . (Round to two decimal places as needed.)