### 9.2 Describing "Average"

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• Math Help

An IQ, or intelligence quotient, is a score from one of the standardized IQ tests used to measure intelligence. The graph below shows the typical range of scores. Note that about 95% of IQ scores lie between 70 and 130, while about 99.7% of the scores lie between 55 and 145. Also, about 16% of the scores are above 115. In Example 6, each estimated IQ is greater than 115.

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• Checkpoint Solution

Adding an IQ score of 200 to the data set will increase the mean from 135 to about 140. Anytime you add numbers to a data set that are larger than the current data, the mean will increase. Likewise, if you add numbers to a data set that are smaller than the current data, then the mean will decrease.

Adding an IQ score of 200 to the data set will change the median from 130.5 to 131. Because the data values are not extremely spread out, adding one number to the set will not greatly affect the median.

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