Since I made a serious, adult student laugh the other day, I thought I would share the tip that did the trick. We were reviewing math for the GMAT (which is the same math as the SAT and GRE, by the way). When we got to the different types of averages, I decided to tell a riddle to help him remember the difference between mean and median, which are two kinds of "averages." Here is the riddle:

Tutor: Did you know that the average salary of geography majors at UNC is over $700,000 per year?

Student: Really?!

Tutor: Yes. That's because Michael Jordan was a geography major at UNC, and there aren't that many geography majors. His enormous multi-million-dollar salary pulled up the average because it was calculated as a mean (everyone's salary added together, then divided by the number of geography majors). However, if you calculated the median instead, by listing all of the salaries in order and finding the middle one, you would get a much more representative number to report as the "average." Medians are very useful when you have a few extreme values that skew the mean to one side. We often hear about median incomes or median home values instead of the means for that reason.

Source: I originally got this riddle/story from Ruth Curran Nield at the Univ. of Pennsylvania, who taught me statistics. She had a nice graph showing the average salaries of different majors at UNC.

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