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 (.02) for the Z score.
Consider an upper-tail test of hypothesis for the difference in two population means. The sample data from the first population is: n = 50, x-bar = 110, s = 10. The sample data from the second population is: n = 75, x-bar = unknown, s = 11. We conclude the alternative hypothesis with a 2% level of significance. Then the value of the second sample mean must be:
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