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The next 4 questions refer to the following situation:

The manager of the service department of a local car dealership has noted that the service times of a sample of 15 new automobiles has a standard deviation of 4 minutes.

I. If we want to determine a 95% confidence interval estimate for the true variance of the service times, what is the "chi-squared " statistics value (use the table).The letter associated with the correct answer is

a) -1.96 and +1.96

b) -2.145and +2.145

c) 7.261 and 24.996

d) 5.629 and 26.119

e)None of the above

II. What is the numerator of the lower and upper limits of the 95% confidence interval for the true variance of the service times?The letter associated with the correct answer is

a) 14

b) 56

c) 112

d) 224

e) None of the above

III. What is the 95% confidence interval for the true variance of the service times?The letter associated with the correct answer is

a) 2.144 to 9.949

b)4.288 to 19.897

c) 8.576 to 39.794

d) 12.689 to 51.875

e) None of the above

IV.What is the 95% confidence interval for the true standard deviation of the service times?The letter associated with the correct answer is

a) 1.464 to 3.154

b) 2.211 to 4.461

c) 2.928 to 6.308

d) 3.562 to 7.202

e) None of the above