A researcher is interested in whether high school students who play sports have a higher or lower body mass index (BMI) than students in the general population. The researcher is unsure whether playing sports will decrease body mass (due to more calories burned) or increase body mass (due to more muscle mass). The researcher selects a sample of 60 athletes and finds that their average BMI is 22. The average (µ) in the general population of students is 22.5 with a standard deviation (s) of 3. What is zobt for this sample?

The standard deviation is a function of how often a set of values variates or disperses. A low baseline means that the values are usually near the mean, whereas a high standard deviation demonstrates that the values are scattered over a larger range.

In the meantime, the critical value of the ZCV or Z (from the z tables) is the spectrum of operation of a hypothesis. Whenever you check the details, measure the mean and alpha values, and check it in the Z Table, if the value z falls between -1.96 and + 1.96 then the conclusion would be right, but if the value falls above and below that value, the hypothesis would be reconsidered in the usual two-top tests.