Question

Confidence Intervals

2.  An auto parts company is interested in how long people plan to own their cars.  They collect the following data by asking 18 car owners how many years they will drive their current car from the time they bought it until they trade it in:

5  7  8  4  9  10  8  5  4  1  6  2  4  3  5  4  3  7

Make a 95% confidence interval for the length of time these car owners will keep their cars.

Answer 1

	Values ( X )
	5	0.0772
	7	2.966
	8	7.4104
	4	1.6328
	9	13.8548
	10	22.2992
	8	7.4104
	5	0.0772
	4	1.6328
	1	18.2996
	6	0.5216
	2	10.744
	4	1.6328
	3	5.1884
	5	0.0772
	4	1.6328
	3	5.1884
	7	2.966
Total	95	103.6116

Mean

Standard deviation

Confidence Interval



Lower Limit =
Lower Limit = 4.0501
Upper Limit =
Upper Limit = 6.5055
95% Confidence interval is ( 4.0501 , 6.5055 )