If X and Y are the respective means of two independent random samples of the same size
Chapter 7, Problem 7.4-15(choose chapter or problem)
If X and Y are the respective means of two independent random samples of the same size n, find n if we want \(\bar x - \bar y \pm 4\) to be a 90% confidence interval for \(\mu_X - \mu_Y\). Assume that the standard deviations are known to be \(\sigma_X = 15\) and \(\sigma_Y = 25\).
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