Suppose that a manager is interested in estimating the average amount of money customers spend in her store. After sampling 36 transactions at random, she found that the average amount spent was $ 32.15 . She then computed a 90 % confidence interval to be between $ 29.18 and $ 35.12 .

Which statement gives a valid interpretation of the interval?

a. The store manager is 95% confident that the average amount spent by the 36 sampled customers is between S31.84 and $38.66.
b. There is a 95% chance that the mean amount spent by all customers is between $31.84 and $38.66.
c. There is a 95% chance that a randomly selected customer will spend between $31.84 and $38.66.
d. The store manager is 95% confident that the average amount spent by all customers is between $31.84 and $38.66