posted by GT on .
Length of Hospital Stays: The average length of “short” hospital stays for men is slightly longer thatn that for women: 5.2 days vs. 4.5 days. A random sample of recent hospital stays for both men and women revealed the following. At ? = 0.01, is there sufficient evidence to conclude that the average hospital stay for men is longer than the average hospital stay for women?
Sample Size 32 30
Sample Mean 5.5 days 4.2 days
Pop. Standard Deviation 1.2 days 1.5 days
Z = (mean1 - mean2)/standard error (SE) of difference between means
SEdiff = √(SEmean1^2 + SEmean2^2)
SEm = SD/√n
If only one SD is provided, you can use just that to determine SEdiff.
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score.