10.45 “Car renters come across steeper rates” (USA Today, May 17, 2005) reported that rates for car rentals are rising but have not surpassed the national average peak of $35.98 a day in 2001. The average national daily rate for the April–June quarter of 2005 was $30.15, yet in some cities, car rentals can cost more than $100 a day. A similar study of two major cities found the following results:

City n Average Daily Rate Std. Dev.

Boston 10 128.25 7.50 New York City 15 116.60 8.90 Set a 95% confidence interval on the difference in average daily rates between the two major East Coast cities of Boston and New York City. Assume normality for the sampled populations and that the samples were selected randomly.