I had my first math exam in 15 years (give or take) on Friday. I had been pretty sick for the preceding week and I came into the exam knowing that I wasn’t going to be able to do my best. (At that point I was pretty happy to be awake and moving, much less able to take an exam.) I took the exam and knew that I was pretty lost on the last page but otherwise it didn’t seem too bad.

We got the exams back on Tuesday and I was pleasantly surprised to see that I got a 87. The class median was 81 and only two people got a 90 or above. However, as I looked over the exam, I found a question that I was pretty sure wasn’t wrong.

To paraphrase the exam question into plain English, you have a kindergarden class of 65 students and you ask the question “What is the student’s gender” for each student. Obviously there are two possible answers, male or female. The exam question asked if you would get every possible answer at least once in the class of 65 students.

The “right” answer was yes. If you take a class of 65 kindergardeners there will be both males and females.

However our professor had spent a day focussing on how unlikely it was that our class has 4 “Andrews” out of the 20 students. During the exam I decided that even though it was highly unlikely that the class would be all male or all female, it was still possible and therefore the answer had to be no since I could come up with a counterexample.

I asked him about it after class today and got him to agree with me. The extra 3 points will get me a 90%, a straight A on the first exam (i.e. before any curving), and a nice start in the class.