Choosing the best average: mean, median or mode

0:00Five friends get this much pocket money each week: 10, 12, 12, 15 and 100 dollars.

0:09Which average describes a typical friend best?

0:13An average is one value that represents a set of data. Three common ones are the mean, the median and the mode.

0:22The mean is the total of the values divided by the number of values.

0:27The total is 10 plus 12 plus 12 plus 15 plus 100, which is 149.

0:35149 divided by 5 is 29.8, and 29.8 times 5 is 149, so the mean is 29 dollars and 80 cents.

0:48The median is the middle of the data when the values are in order, from smallest to largest. These already are.

0:56The third of the five values is the middle, with two on each side. So the median is 12 dollars.

1:04The mode is the value that occurs most often. 12 dollars appears twice, so the mode is 12 dollars.

1:11On a number line, 100 dollars is far from the rest. A value like this is called an outlier.

1:20The outlier pulls the mean up to 29 dollars and 80 cents, but four of the five friends get 15 dollars or less.

1:28The median stays at 12 dollars, so here it describes a typical friend best.

1:35For shoe sizes sold in a store, the mode is most useful: the size sold most often is the one to stock most.

1:44A common mistake is to always choose the mean. Check for outliers first.

1:49Recap: choose the average that fits the data, not always the mean.