The maintenance crew of a hotel must monitor the temperature of the hotel pool and hot tub. To enhance comfort, the management team requests that the mean pool temperature and the mean hot tub temperatures not differ by more than 15 degrees. To estimate the difference in these mean temperatures the maintenance crew selects a random sample of 8 times to check the hot tub temperature and a random sample of 10 times to check the pool temperature. Although the sample sizes are small, the distribution of temperature for the pool and for the hot tub does not show strong skewness or any outliers. What is the appropriate inference procedure? t confidence interval for a mean z confidence interval for a proportion t confidence interval for a difference in means z confidence interval for a difference in proportions