According to an investigative reporter (Jim Drinkard, “Legislators Want to Ground ’Fact-Finding’ Trips,” USA Today, January 19, 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.
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.