In trying to understand the impacts of caffeine on consumer spending, researchers in France ran the following experiment: 145 people walking into a home goods store were offered a welcome beverage: an espresso (caffeinated) or an

option of a non-caffeinated drink. 58 shoppers chose the espresso while 87 went for the non -caffeinated alternative. On average the caffeinated shoppers spent $18 with a standard deviation of $29, while the non- caffeinated folks

spent on average $9 with a standard deviation of $16.

Which statement is correct?

a. The upper end of the 95% confidence interval for the average of caffeinated shoppers is $78 approximately.

b. The 95% confidence interval for the average of caffeinated shoppers is narrower than the 95% confidence interval for the average of non-caffeinated shoppers

c. the 99% confidence intervals for the average spending of the two groups of shoppers overlap