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 Description  
 Median:  The number in the middle of a set of data when the data are arranged in order. When there are two middle numbers, the median is their mean.

(To help you remember what the median is, think of the median that is in the middle of the road.)

The first step in finding the median is to arrange the data in either decreasing or increasing order. Let's arrange the mathematics test scores for two classes in increasing order.

Class 1: 49, 54, 55, 65, 76, 76, 76, 78, 78, 81, 83, 85, 88, 89, 89, 90, 90, 91, 93, 99

Class 2: 55, 59, 60, 65, 68, 76, 77, 77,78, 80, 80, 80, 89, 89, 90, 92, 92, 95, 96, 98

Since there are 20 test scores for each class, there are two "middle" scores, the tenth and the eleventh. We average the tenth and eleventh scores to find the median.

(Median for Class 1)
 
(Median for Class 2)
 

Based on the medians, it appears that Class 1 did better than Class 2 on the mathematics test. Also, notice that the median for Class 1 (82) is not equal to an actual score from Class 1. Thus, if there is an even number of scores, the median may not be equal to an actual score from the data.

Do you think the median is affected by extreme scores like the mean is?