Answer:
With a 0.01 significance level and samples of 50 and 40 cofee drinkers, there is enough statistical evidence to state that the mean daily consumption of regular-coffee drinkers is less than that of decaffeinated-coffee drinkers.
The test is a one-tailed test.
Step-by-step explanation:
To solve this problem, we run a hypothesis test about the difference of population means.
The appropriate hypothesis system for this situation is:
Difference of means in the null hypothesis is:
Since, the calculated statistic is less than critical
, the null hypothesis should be rejected. There is enough statistical evidence to state that the mean daily consumption of regular-coffee drinkers is less than that of decaffeinated-coffee drinkers.