4. (20 points) Hoping to lure more shoppers downtown, a city builds a new public parking garage in the central business district. The city plans to pay for the structure through parking fees. During a two-month period (44 weekdays), daily fees collected averaged $126, with a standard deviation of $15.

(a) a 90% confidence interval for the mean daily income this parking garage will generate.

(b) Interpret this confidence interval in context.

(c) What assumptions must you make in order to do the inference?

(d) The consultant who advised the city on this project predicted that parking revenues would average $130 per day. Based on your confidence interval, do you think the consultant was correct? Why?