Question

Use the pulse rates for a random sample of adult women listed below to determine a 90% confidence interval estimate for the population average pulse rate for all adult women. Assume that pulse rate is normally distributed.

83. 58 70 56 76 64 80 76 70 97 68 78 108

Use the data above, find an 80% confidence interval estimate for the population variance in pulse rate.

Answer 1

X	(X - Mean(X))^2
58	291.840276638889
70	25.840277438889
56	364.173609838889
76	0.840277838888878
64	122.840277038889
80	24.1736114388888
76	0.840277838888878
70	25.840277438889
97	480.340279238889
68	50.173610638889
78	8.50694463888885
108	1083.50694663889
901	2478.91666666667

First we compute the sample mean as:

Now the sample standard deviation is computed as:

Now for n-1 = 11 degrees of freedom, we get from the chi square tables:

Therefore the confidence interval for population variance here is computed as:

This is the required confidence interval.