A professor in the psychology department would like to determine whether there has been a significant change in grading practices over the years. It is known that the overall grade distribution for the department in 1985 had 14% As, 26% Bs, 31% Cs, 19% Ds, and 10% Fs. A sample of n=200 psychology students from last semester produced the following grade distribution:
A B C D F
32 61 64 31 12
Does the data indicate a significant change in the grade distribution? Test at the .05 level of significance. Again multiply 200 by the expected proportions given in the problem(i.e. 14%, 26%,... etc) to get the expected frequencies. Then use the formula to compute chi square.