Use the one-standard-deviation chi-square interval procedure to obtain the specified confidence interval for thepopulation standard deviation Ϭ. Assume that the population has a normal distribution.
-A sociologist develops a test to assess attitudes about public transportation, and 27 randomly selected subjects are given the test. Their mean score is 76.2 and their standard deviation is 21.4.
Construct a 95% confidence interval for the standard deviation, Ϭ, of the scores of all subjects.
A)17.5 to 27.8
B)16.9 to 29.3
C)16.6 to 28.6
D)17.2 to 27.2

Question

Use the one-standard-deviation chi-square interval procedure to obtain the specified confidence interval for thepopulation standard deviation Ϭ. Assume that the population has a normal distribution.
-A sociologist develops a test to assess attitudes about public transportation, and 27 randomly selected subjects are given the test. Their mean score is 76.2 and their standard deviation is 21.4.
Construct a 95% confidence interval for the standard deviation, Ϭ, of the scores of all subjects. 
A)17.5 to 27.8
B)16.9 to 29.3
C)16.6 to 28.6
D)17.2 to 27.2

Quizplus · Accepted Answer

The chi-square distribution is used to construct the confidence interval for the population standard deviation. With 27 subjects, the degrees of freedom is 26. Using the chi-square distribution table, the critical values for a 95% confidence interval are found, and the interval is calculated using the sample standard deviation.

Use the One-Standard-Deviation Chi-Square Interval Procedure to Obtain the Specified