Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter 3 - Section 3.5 - Exponential Growth and Decay; Modeling Data - Exercise Set - Page 508: 70

Answer

a. $y=201.2(1.011)^x$ see explanations. b. $y= 201.2 e^{0.0109x}$, $1.1\%$

Work Step by Step

a. Plot the data and use $y=ab^x$ to fit; we can get $a=201.2, b=1.011, r=0.999$, that is $y=201.2(1.011)^x$ as shown in the figure. As $r$ is close to $1$, it indicates a very good fit using the model. b. We can rewrite the model as $y=ab^x=ae^{ln(b^x)}=201.2 e^{ln((1.011)^x)}=201.2 e^{x\ ln1.011}=201.2 e^{0.0109x}$ The increasing percentage each year can be found as $\frac{y(1)}{y(0)}-1=e^{0.0109}-1\approx0.011$ or $1.1\%$
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