Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Chapter 13 - Counting and Probability - Chapter Review - Review Exercises - Page 868: 3



Work Step by Step

According to the counting formula we know that $n(A\cup B)=n(A)+n(B)-n(A\cap B).$ Hence here $30=12+n(B)-6\\n(B)=30-12+6=24.$
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