Thursday, March 14, 2013

How many above the mean?

Robert was challenged by a question regarding the following scenario: consider a skating rink with 200 skaters. How many are skating above the average speed? He first assumed that about half would be skating the average speed, and therefor a quarter (50) would be skating faster than the average speed.

I asked Robert to consider the batting average of a baseball player. If a player had an average of .285, how many games does he actually bat .285? Robert had to think this one through for a minute, but then suggested that the baseball player will not have any days of batting exactly .285; this is just the average of all his days.

After this, he had a better understanding of what the mean measures. He came to the conclusion that half of the skaters would be skating above the average speed (assuming an even distribution of speeds above and below the mean).

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