Z = (mean1 - mean2)/Standard Error of difference between means.
SEdiff = √(SE^2 of mean1 + SE^2 of mean2)
SE^2 = SD^2/(n-1)
Since you only have SE for one mean, use that as your best estimate.
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion = to Z score.
An article (N. Hellmich. "'Supermarket Guru' Has a Simple Mantra,” USA Today, June 19, 2002, p. 70) claimed that the typical super market trip takes a mean of 22 minutes. Suppose that in an effort to test this claim, you select a sample of 50 shoppers at a local supermarket. The mean shopping time for the sample of 50 shoppers is 25.36 minutes with a standard deviation of 7.24 minutes. Using the 0.10 level of significance, is there evidence that the mean shopping time at the local supermarket is different from the claimed value of 22 minutes?
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