# Probabilty & Statistic

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A random sample is selected from a normal population with a mean of __40 and a standard deviation of __10. After a treatment is administered to the individuals in the sample, the sample mean is found to be M _ 42.
a. How large a sample is necessary for this sample mean to be statistically significant? Assume a two tailed test with _ = .05
b. If the sample mean were M _ 41, what sample size is needed to be significant for a two-tailed test with _ = .05.

• Probabilty & Statistic -

mean 100 standard deviation 20 population 1000

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