Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

Published by Pearson
ISBN 10: 0-32193-104-1
ISBN 13: 978-0-32193-104-7

Chapter 12 - Counting and Probability - Section 12.1 Counting - 12.1 Assess Your Understanding - Page 867: 13


$n(A) = 40$

Work Step by Step

From the formula $n(A\cup B) = n(A) + n(B) - n(A \cap B)$ solve for $n(A)$ to obtain: $n(A\cup B) = n(A) + n(B) - n(A \cap B) \\n(A\cup B) +n(A \cap B) - n(B)=n(A) \\n(A)=n(A\cup B) +n(A \cap B) - n(B)$ Using the formula above gives: $n(A)= n(A\cup B) +n(A \cap B) - n(B) \\n(A)= 50+ 10 -20 \\n(A)= 40$
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