Question

PART I

Internet speeds are a heavily advertised selling point of Internet Service Providers. You notice that although you are paying for a certain speed, the true speed seems to vary depending on where you are in your house. In order to estimate the true average speed you are getting in your house, you go to 12 random spots around your house and record the speed (in MBs per second) shown from a test at 'www.speedtest.net'. You see that the average is 7.36 MB/s with a standard deviation of 1.006 MB/s. You decide to create a 90% confidence interval for the average internet speed in your house. What is the margin of error for this estimate?

1)

0.2904

2)

0.3959

3)

0.5215

4)

0.388

5)

0.5176

PART II

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 9 cars, the average wait time is 9.843 minutes with a standard deviation of 1.4625 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.

1)	( 8.949 , 10.737 )

2)	( -8.936 , 10.75 )

3)	( 8.936 , 10.75 )

4)	( 7.983 , 11.703 )

5)	( 9.355 , 10.331 )

PART III

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 13 cars, the average wait time is 6.499 minutes with a standard deviation of 1.3472 minutes. Construct a 95% confidence interval for the true average wait time for a car at the intersection between 4:00 PM and 5:00 PM.

1)	( -5.685 , 7.313 )

2)	( 6.125 , 6.873 )

3)	( 4.32 , 8.678 )

4)	( 5.692 , 7.306 )

5)	( 5.685 , 7.313 )

Answer 1