: Human Resources took a survey and found that the average commute time one way is 25.4 minutes. However one of the executives feels that the commute is less. He randomly selects 25 commuters and finds that the average is 22.1 minutes with a standard deviation of 5.3 minutes. At ƒÑ=0.10, is he correct?

Question

:   Human Resources took a survey and found that the average commute time one way is 25.4 minutes.  However one of the executives feels that the commute is less.  He randomly selects 25 commuters and finds that the average is 22.1 minutes with a standard deviation of 5.3 minutes.  At ƒÑ=0.10, is he correct?

PsyDAG · Answer

I don't know what "ƒÑ" means.

Z = (mean1 -mean2)/Standard Error (SE) of the mean

SE = SD/√(n-1)

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to that Z score.