Question

A city's mayor plans to build a new public parking garage in order to lure more shoppers in the area. They plan to pay for this structure with the money collected from parking fees. For a random sample of 42 weekdays, the average daily fee collected was $132.40 with a standard deviation of $17.5. Find the following for a confidence interval of a population mean, μ:

a) The margin of error (bound on the error of estimation) at an 80% confidence level. Round answer to 3 decimal places.

b) Construct the 80% confidence interval. Round the endpoints to 2 decimal places.

Answer 1

given data are:-

a). df = (n-1) = (42-1) = 41

t critical value for alpha= 0.20, df= 41 , both tailed test be:-

( using excel )

the margin of error (bound on the error of estimation) at an 80% confidence level is :-

b). the 80% confidence interval is:-

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