2. Amidala is an associate professor at Theed CC. To break up the monotony of her commute, Amidala decides to estimate
the mean number of times she is stopped by a red light on her way to campus. She randomly selects 36 days in her work
schedule and records the number of red lights she hit. The data showed an average of 7.78 red lights with a standard
deviation of 2.17 red lights.
(a) Estimate with 95% confidence the average number of red lights Amidala approaches on her drive to campus.
(b) What is the margin of error associated with the estimate? Explain its meaning.
(c) A civil engineer who works at the college told Amidala city planners program the lights so that commuters hit less
than 9 red lights on average following her typical route to the school. Does his assertion seem reasonable? Justify
your response.
(d) If we assume the standard deviation for the number of red lights is actually 1.45, what size sample should she use to
estimate the true number of red lights to within 0.25 stops at the 95% level of confidence?