# Power Calculations?

You are designing a study to test the null hypothesis that μ = 0 versus the alternative that μ is positive. Assume that σ is 15. Suppose that it would be important to be able to detect the alternative μ = 2. Perform power calculations for a variety of sample sizes and determine how large a sample you would need to detect this alternative with power of at least 0.80.

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I don't see a question mark. –  joriki Sep 28 '12 at 5:08
looks like a homework. You should add the corresponding tag. –  Cristian Sep 28 '12 at 5:11
Are you aware that there is a stackexchange site for statistics, called CrossValidated? –  Gerry Myerson Sep 28 '12 at 5:58
Ignoring comments is an efficient method of deterring potential respondents. –  joriki Sep 30 '12 at 15:01