Practice Problems: Measures of Central Tendency - Answer

Data	Array
87	99
99	94
75	93
87	88
94	87
75	87
35	87
88	75
87	75
93	35

Mean

Mean =

X / N =

820 / 10 =

82.0

Median

35

75

75

87

87

87

88

93

94

99

The median is 87. Half of the scores fall above this number and half fall below.

Mode

Mode is equal to 87. It occurs 3 times; all other scores occur only 2 times or less

What does this information tell you about students' performance on the midterm (the traditional grading scale is used)?

The mean grade on the midterm was an 82 (a low B). Half of the students had a test score above 87 (a high B or an A). Half the students' scores were lower than an 87. The most common test score was an 87 (a high B).

Is this data skewed?

Yes, this data is skewed (a negative skew). The score of 35 is an extreme score (outlier), has caused the skew, and distorts the mean.