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 - 3-3 Measures of Variation - Basic Skills and Concepts - Page 111: 41


a) 95% b)68%

Work Step by Step

a) By the empirical rule, 95% of the data are within 2 standard deviations of the mean, hence the answer is 95%. b) $|280-215|=|280-345|=65=standard \ deviation$, hence by the empirical rule, 68% of the data are within 1 standard deviation from the mean, hence the answer is 68%.
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