<Li> These scores are converted to percentiles (or some other system of quantiles). </Li> <Li> The percentile values are transformed to grades according to a division of the percentile scale into intervals, where the interval width of each grade indicates the desired relative frequency for that grade . </Li> <P> For example, if there are five grades in a particular university course, A, B, C, D, and F, where A is reserved for the top 20% of students, B for the next 30%, C for the next 30% - 40%, and D or F for the remaining 10% - 20%, then scores in the percentile interval from 0% to 20% will receive a grade of D or F, scores from 21% to 50% will receive a grade of C, scores from 51% to 80% receive a grade of B, and scores from 81% to 100% will achieve a grade of A . </P> <P> Consistent with the example illustrated above, a grading curve allows academic institutions to ensure the distribution of students across certain grade point average (GPA) thresholds . As many professors establish the curve to target a course average of a C, the corresponding grade point average equivalent would be a 2.0 on a standard 4.0 scale employed at most North American universities . Similarly, a grade point average of 3.0 on a 4.0 scale would indicate that the student is within the top 20% of the class . Grading curves serve to attach additional significance to these figures, and the specific distribution employed may vary between academic institutions . </P>

What does top of the bell curve mean