Question: Confidence Interval for Standard Deviation

Shown are the ages in years of the presidents at the time of their deaths.

67 90 83 85 73 80 78 79

68 71 53 65 74 64 77 56

66 63 70 49 57 71 67 71

58 60 72 67 57 60 90 63

88 78 46 64 81

? Do the data represent a population or a sample?

? Select a random sample of 12 ages and find the variance and standard deviation.

? Find the 95% confidence interval of the standard deviation.

? Find the standard deviation of all the data values.

? Does the confidence interval calculated in question 3 contain the mean?

? If it does not, give a reason why.

? What assumptions must be considered for constructing the confidence interval in step 3?