Question

Suppose you are a civil engineer, specializing in traffic volume control for the City of Grand Rapids. Your department has been receiving a multitude of complaints about traffic wait times for a certain intersection in the heart of downtown. To see if these claims are valid, you want to monitor the true average wait time at that intersection. Over the course of a few months, you record the average number of minutes a car waits at the intersection between 4:00 PM and 5:00 PM. With a sample size of 10 cars, the average wait time is 8.154 minutes with a standard deviation of 1.9785 minutes. Construct a 90% confidence interval for the true average wait time for a car at the intersection between 4:00 PM and 5:00 PM.

Question 6 options:

	1) ( 7.528 , 8.78 )
	2) ( 6.321 , 9.987 )
	3) ( 7.007 , 9.301 )
	4) ( -7.007 , 9.301 )
	5) ( 7.02 , 9.288 )

Answer 1

The statistic software output for this problem is:

One sample T summary confidence interval: u: Mean of population 90% confidence interval results: Mean Sample Mean Std. Err. DF L. Limit U. Limit 8.154 0.62565664 97.0071007 9.3008993

The 90% CI is :

(7.007 , 9.301)