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Two-Sample Z-Test for μ₁−μ₂

Overview

Tests whether two population means differ when both population variances are known.

Test Statistic

\[ Z = \frac{(\bar{X}_1 - \bar{X}_2) - \delta_0}{\sqrt{\sigma_1^2/n_1 + \sigma_2^2/n_2}} \]

where \(\delta_0\) is the hypothesized difference (usually 0).