Elementary Statistics (12th Edition)

Published by Pearson
ISBN 10: 0321836960
ISBN 13: 978-0-32183-696-0

Chapter 3 - Statistics for Describing, Exploring, and Comparing Data - 3-4 Measures of Relative Standing and Boxplots - Basic Skills and Concepts: 9

Answer

The z scores are -2 and 2, the IQ scores are 70 and 130.

Work Step by Step

If a value is unusual, then it is more than two standard deviations far from the mean. $Minimum \ usual \ value=mean-2\cdot(standard \ deviation)=100-2\cdot15=70$ $Maximum \ usual \ value=mean+2\cdot(standard \ deviation)=100+2\cdot15=130$. Therefore the z scores are -2 and 2, the IQ scores are 70 and 130.
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