This document explains how to perform a z-test for two sample means. The z-test can be used to determine if the difference between the means of two random samples from a normal population is statistically significant. The document provides the formula for the z-test and walks through an example comparing the average monthly family incomes from two neighborhoods based on random samples. It demonstrates stating the null and alternative hypotheses, performing the z-test calculation, comparing the results to the critical value, and making a conclusion about rejecting or failing to reject the null hypothesis based on the level of significance.