College Algebra (10th Edition)

Published by Pearson
ISBN 10: 0321979478
ISBN 13: 978-0-32197-947-6

Chapter 9 - Section 9.3 - Geometric Sequences; Geometric Series - 9.3 Assess Your Understanding - Page 665: 86


${{\$}} 6655.58$

Work Step by Step

Decreasing x by $ 15\%$ is multiplying it with $1-0.15=0.85.$ $a_{1}=15,000$ $a_{2}=15,000(0.85)$ $a_{3}=15,000(0.85)^{2}...$ This is a geometric series with $a_{1}=15,000$, $r=0.85,\ \quad a_{n}=a_{1}r^{n-1}$ We want $a_{5}=15,000(0.85)^{4}\approx 6655.58$
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