I took all of the raw scores, which were out of 181 points, and averaged them. The average was 116, which was about 64%.
From that average I found the standard deviation to be about 33. For more on this means, read the wikipedia article.
Now I "binned" all of the students' grades. If a student was within one-half the standard deviation either above or below the mean, that person was put in the "B" bin. If the student was above a half-standard-deviation above the average, that student was put in the "A" bin. Maybe this will be clearer as a list.
Standard deviation is s. The student grade is g. The average is v.
- g > v + s --- A+ ---- 98-100
- v + s/2 < g < v + s --- A --- 90-97
- v - s/2 < g < v + s/2 --- B --- 80-89
- v - s < g < v - s/2 --- C --- 70-79
- v - 2s < g < v - s --- D --- 60-69
- g < v - 2s --- below -- 50-59
Within each bin the grades were scaled to fit the final score range of that bin. For example, all the grades in the "B" bin ranged from 104 to 129. That is a range of 25 points. I re-mapped that range to the range of "B" class final scores, which is 80-89, with this simple formula:
(g-104)/24)*9)+80
I repeated this with all the bins, and that is how you got your grade. The final distribution was:
- 7 A+
- 11 A
- 24 B
- 6 C
- 2 D
- 5 below
Any questions, come see me. If you think you've been mis-graded, come see me. I know of one question where I misinterpreted some student's answers. If you think you got it right but scored abysmally on one section, it might be you.
