There is concern about the speed of automobiles travelling over a particular stretch of highway. For a randomsample of 28 automobiles, radar indicated the following speeds in miles per hour
59 63 68 57 56 71 58 69 53 55 60 67 51 59
53 64 56 57 66 61 65 70 64 65 57 56 61 59
a. Check the evidence of non normality
b. Find a point estimate of the population mean that is unbiassed and efficient
c. Use an unbiassed estimation procedure to find a point estimate of the variance of the sample mean.