Following are weights of 12 two-month-old baby girls. Assume that the population is normally distributed.

a. Find the sample standard deviation s.

b. Construct a 95% confidence interval for the population standard deviation σ.

c. According to the National Health Statistics Reports, the standard deviation of the weight of two-month-old baby boys is 2.7 pounds. Based on the confidence interval, is it reasonable to believe that the standard deviation of the weights of two-month-old baby girls is the same as that of two-month-old baby boys? Explain.

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12.23 12.32 11.87 12.34 11.48 12.66 8.51 14.13 12.95 10.30 9.34 8.63