When grading using “the curve”, the percentages are as follows:
A: Top 10% of scores
B: Scores between P70 and P90
C: Middle 40% (scores between P30 and P70)
D: Scores between P10 and P30
F: Bottom 10% of scores
CLASS #1: Suppose that the exam grades for Class #1 are as follows:
35 44 46 47 48 51 54 55 55 57
57 58 59 60 60 60 60 61 62 64
68 69 70 72 73 75 75 77 82 85
µ = 61.3 standard deviation = 11.5
a) Using the mean and standard deviation above and the invNorm feature of your calculator,
determine “the curve” cutoffs for the PK values listed above. (These are not standard deviations.)
Round these test grade cutoffs to one decimal. Label them underneath the curve.
Test Grades 0100

b) Use the one-decimal place cut-offs in the picture you created in part (a) to fill in the chart below
with the new range of scores for each letter grade under this plan. Then, look at the 30 test grades
and count how many test grades would fall in each letter grade based on the new scale.

Letter Grade Range of Scores Number of Tests
A to 100
B
C
D
F 0 to