Parking, part 2.

Suppose that for budget planning purposes the city in Exercise 29 needs a better estimate of the mean daily income from parking fees.

a) Someone suggests that the city use its data to create a 95% confidence interval instead of the 90% interval first created. How would this interval be better for the city?

(You need not actually create the new interval.)

b) How would the 95% confidence interval be worse for the planners?

c) How could they achieve a confidence interval estimate that would better serve their planning needs?