A university investigation was conducted to determine whether women and men complete medical school in significantly different amounts of time, on the average. Two independent random samples were selected and the following summary information concerning times to completion of medical school computed:

	Women	Men
Sample Size	90	100
Sample Mean	8.4 years	8.5 years
Sample Standard Deviation	0.6 years	0.5 years

Compute the test statistic to test the null and alternate hypothesis:

H0: vs. Ha: mu1-mu2 not equal 0