A coffee manufacturer is interested in whether the mean daily consumption of regular-coffee drinkers is less than that of decaffeinated-coffee drinkers. Assume the population standard deviation for those drinking regular coffee is 1.29 cups per day and 1.44 cups per day for those drinking decaffeinated coffee. A random sample of 55 regular-coffee drinkers showed a mean of 4.41 cups per day. A sample of 47 decaffeinated-coffee drinkers showed a mean of 5.16 cups per day.
Use the .02 significance level.