We have already done a few Z-tests before where we validated our null hypothesis.
A T-distribution is similar to a Z-distribution—it is centered at zero and has a basic bell shape, but its shorter and flatter around the center than the Z-distribution.
The T-distributions' standard deviation is usually proportionally larger than the Z, because of which you see the fatter tails on each side.
The t distribution is usually used to analyze the population when the sample is small.
The Z-test is used to compare the population mean against a sample or compare the population mean of two distributions with a sample size greater than 30. An example of a Z-test would be comparing the heights of men from different ethnicity groups.
The T-test is used to compare the population mean against a sample, or compare the population mean of two distributions with a sample size less than 30, and when you don't know the population's standard deviation.
Let's do a T-test on two classes that are given...