A teacher figures that final grades in the statistics department are distributed as: A, 25%; B, 25%; C, 40%; D, 5%; F, 5%. At the end of a randomly selected semester, the following number of grades were recorded. Find the critical value to determine if the grade distribution for the department is different than expected. Use %u03B1 = 0.01. Solution Here we should use a Chi-Square test for Goodness of fit. Since there are 5 groups, the d.f. of the Chi-Square statistic is k - 1 = 5 - 1 = 4. Thus, at alpha = 0.01, from Chi-Square Tables, we get the critical value as 13.277. Note that if in any of the classes the expected frequency is less than 5, we should club the adjecent classes to find the degrees of freedom of the test statistic..