College Algebra 7th Edition

Published by Brooks Cole
ISBN 10: 1305115546
ISBN 13: 978-1-30511-554-5

Chapter 4, Exponential and Logarithmic Functions - Section 4.6 - Modeling with Exponential Functions - 4.6 Exercises - Page 415: 14

Answer

(a). $r=104\%$ (b). $n_0=50$ (c). $n(t)=50e^{1.04t}$ (d). $n(4.5)=5388.5$ (e). $t=6.64$

Work Step by Step

$n(t)=n_0\times e^{rt}$. Whereas,$n(t)$ is population at time $t$, $n_0$ is Initial size of the population, $r$ is relative rate of growth, and $t$ is time. (a). $n(2)=n_0e^{2r}=400$, $n(6)=n_0e^{6r}=25,600$. $\frac{n(6)}{n(3)}=\frac{e^{6r}}{e^{2r}}=64,$ $e^{4r}=64,$ $4r=\ln 64,$ $r=1.04$ or $r=104\%$ (b). $n(2)=n_0e^{2r}=400$. $n_0=\frac{400}{e^{2.08}}=50,$ (c). $n(t)=50e^{1.04t}$ (d). $n(4.5)=50e^{1.04t\times 4.5}=5388.5$ (e). $50,000=50e^{1.04t},$ $e^{1.04t}=1000,$ $1.04t=\ln 1000$ $t=6.64$
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