Monday, March 26, 2007

Exam II scores and distribution.

The second exam is graded, and it went better than expected. The average was 84.64% with a standard deviation of 12.41%, so there was no need for scaling. The usual 90/80/70/60 scale applies.

In the end, each of the 8 questions you answered was worth 10 points, for a total of 80 points. Full credit on the bonus question was 5 points extra. Heavy partial credit was given, including on the bonus question. Below is the grade scale out of 80, for convenience:

> 72/80 = A
> 64/80 = B
> 56/80 = C
> 48/80 = D
< 48/80 = F

Pluses and minuses are given at +/- 2.5% from the grade breaks (e.g., 97.5% = A+, 87.5% = B+, 92.5=A-).

Below is the histogram for the exam. Quite a few A's and C's. There were only 3 failing grades, and the lowest of those was only 5 points from passing - 5 points which can easily be made up if you rock the homework (hint, hint).

Next is a plot showing the percentage of students choosing each problem, and the average score for that problem. Clearly, numbers 1, 8, and 9 were tough. Numbers 10 and 12 were sleepers - the few who answered them did very well, disproportionately so, but they were largely ignored. Otherwise, there were no surprises as to which problems you chose, and the scores were in proportion.

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