Question 13 • Concepts in Probability and Statistics A
Sora was given two data sets, one without an outlier and one with an outlier. Data without an outlier: 108, 113, 105, 118, 124, 121, 109Data with an outlier: 108, 113, 105, 118, 124, 121, 109, 41How is the mean affected by an outlier?
Answer
A
The outlier did not affect the mean at all.
B
The outlier made the mean higher than all the other values.
C
The outlier made the mean lower than all the other values.
D
The mean is centered around all the other numbers in both sets of data.
Explanation
The value 41 is much lower than the other data values, which range from 105 to 124, so it pulls the mean downward. Without 41, the mean is 798 ÷ 7 = 114; including it, the mean is 839 ÷ 8 = 104.875. Therefore, the outlier made the mean lower than the other values, as choice C says.
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