This is concern about the speed of automobiles traveling over a particular stret

Question

This 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 68 57 56 72 58 69 52 55 60 66 51 59

53 64 58 57 66 61 65 70 64 65 57 56 61 59

a. Check for evidence of nonnormality.

b. Find a point estimate of the population mean that is unbiased and efficient.

c. Use an unbiased estimation procedure to find a point estimate of the variance of the sample mean.

____________________________________________________________________________________

a. Is there evidence of nonnormality? (check correct answer)

A. No, because the normal probability plot of the data deviates from a straight line.

B. Yes, because the normal probability plot of the data is reasonably close to a straight line.

C. Yes, because the normal probability plot of the data deviates from a straight line.

D. No, because the normal probability plot of the data is reasonably close to a straight line.

b. An unbiased and efficient point estimate of the population mean is ____. (round to two decimal places as needed and show your work)

c. A point estimate of the variance of the same mean is _____. (round to two decimal places as needed and show your work)

Explanation / Answer

(A) No, because the normal probability plot of the data is reasonably close to a straight line. Option D is correct.

(B) The unbiased and efficient pont estimate of the population means is the sample mean, which is equals to 60.71.

Sample mean = Sumof all numbers/ 28 = 60.71

(C) Point estimate of the variance of the same mean is equal to variance of the given sample, which is equals to

Variance = 30.80

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