In: Statistics and Probability
Suppose that we randomly select 50 billing statements from each of the computer databases of the Hotel A, the Hotel B, and the Hotel C chains, and record the nightly room rates. The means and standard deviations for the data are given in the table.
| Hotel A | Hotel B | Hotel C | |
|---|---|---|---|
| Sample Average ($) | 140 | 180 | 120 | 
| 
Sample Standard Deviation  | 
17.7 | 22.6 | 12.5 | 
(a) Find a 95% confidence interval for the difference in the average room rates for the Hotel A and the Hotel B chains. (Use Hotel A − Hotel B. Round your answers to two decimal places.)
$______ to $______
(b)Find a 99% confidence interval for the difference in the average room rates for the Hotel B and the Hotel C chains. (Use Hotel B − Hotel C. Round your answers to two decimal places.)
$______ to $______