One statistical technique to determine if a sample’s mean deviates significantly from an assumed or known population mean is the Z-test. The Z-test, which is used in hypothesis testing, entails figuring out the Z-score, which expresses how far a data point deviates from the mean in standard deviations. An elevated Z-score indicates a noteworthy departure from the average. When the population standard deviation is known, this test is very helpful. The Z-test is a widely used statistical tool in many disciplines, including psychology, economics, and quality control.