A researcher is interested in whether 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). This is a _____ -tailed test and the zcv is _____.

Answer:This is a TWO-tailed test and the zcv is +/- 1.96.Step-by-step explanation:When we talk about two tailed tests in applied statistics, we are talking about a test method in  which the critical area of a distribution is observed both when is greater and less than an observed range of values.It is important for checking null-hypothesis and testing for statistical significance.In this example since you want to know whether students who play sports have HIGHER or LOWER BMI than students who do not exercise, then you need to check the cases at the "back tail" of the distribution and at the "front tail" thus making it a two tailed test, in order to check if there is an effect from calorie burning or increased body mass, compared to a regular Joe.Meanwhile, the ZCV or Z critical Value (from the z tables), is the "range" in which the hypothesis would be applicable. In standardized two tailed testing, a value of 1.96 is usually taken to delimit the reject regions in which the testing will fail, meaning that when you check the data, calculate the mean and alpha values, and then check them in the Z-table, if the z value falls in between -1.96 and +1.96 then the hypothesis would be correct, but if it falls above or bellow those values, the hypothesis would be rejected.