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Confidence Interval

8-76. According to an investigative reporter (Jim Drinkard - Legislators want to Ground 'Fact-finding' Trips, USA Today, January 2006), members of Congress are coming under scrutiny for 'fact-finding' trips. Since 2000, members of Congress have made 6,666 trips paid for by private interests. The trips were worth about $19.6 million.

a. Calculate the average cost of these fact finding trips.

b. If the cost of the trips could be considered to have a normal distribution, determine the standard deviation of the cost of the trips. (Hint: Recall the Empirical Rule).

c. Choose a reasonable confidence level and calculate a confidence interval for the average cost of congressional fact-finding trips from the year 2000 until January 19, 2006.

Solution Summary

The solution describes the determination of average cost standard deviation and confidence interval for the cost of the trips.