Example: A sample data (X = 36.8, N = 30) was drawn from a population of raw scores with = 33 and = 12. Use the criterion of 0.05 ( = 0.05) for the upper tail, conduct the necessary statistical analysis to determine whether the sample falls in the region of rejection. a) Step 1: (Optional) Draw a quick illustration. I personally find it helpful to draw a quick illustration when trying to solve this type of problem. (1) Critical value of z is a positive number (upper tail), 2, critical value of z (lower tail), 3. Critical value of Z