A tried-and-true revenue stream for large cities has been the funds collected from parkingn meters. In a random sample of 21 meters, the mean amount collected was $127 per meter with a standard deviation of $34. You want to estimate the mean amount collected by all parking meters in the city.
a) Which type of interval should you use? z-interval t-interval
b) Estimate the mean amount spent by shoppers at the store, with 90% confidence.
c) Explain/Interpret your confidence interval in simple language in context of the problem.
d) What assumption about at the distribution of amounts must be true in order for your confidence interval to be valid?