Functions Modeling Change: A Preparation for Calculus, 5th Edition

Published by Wiley
ISBN 10: 1118583191
ISBN 13: 978-1-11858-319-7

Chapter 4 - Exponential Functions - 4.2 Comparing Exponential and Linear Functions - Exercises and Problems for Section 4.2 - Exercises and Problems - Page 156: 40

Answer

$ T= 24071+602.3t $ $ T(t)=24071(1.02258)^t $

Work Step by Step

A) Take $t= 0$ for 2003 so that $t= 10$ corresponds to the 2013. Let $T= b+mt$, then $T= 24071+m\cdot0 = 24071=b$. We find the slope from: $$ m=\frac{\Delta T}{\Delta t}=\frac{30094-24071}{10-0}=602.3 $$ The required formula is $$ T= 24071+602.3t $$ B) Let $T(t)=a(b)^t $ for the exponential function of tuition growth in the US. The value of $a$ can be taken directly from problem as $a= 24071$. We now have $N(t)= 24071(b)^t$. Use the point (10,30094) to find the value of $b$. $$ \begin{aligned} 24071(b)^{10}& =30094 \\ b^{10} & =\frac{30094}{24071}=1.2502\\ b & =(1.2502)^{1 / 10}=1.02258 \end{aligned} $$ The required formula is $$ T(t)=24071(1.02258)^t $$
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