A hair salon in Cambridge, Massachusetts, reports that on seven randomly selected weekdays, the number of customers who visited the salon were 40, 3 0 , 2 8 , 2 2 , 3 6 , 16, and 50. It can be assumed that weekday customer visits follow a normal distribution.

a. Construct a 90% confidence interval of the average number of customers who visit the salon on weekdays.

b. Construct a 99% confidence interval of the average number of customers who visit the salon on weekdays.

c. What happens to the width of the interval as the confidence level increases? P-69