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 4 - Exponential and Logarithmic Functions - Section 4.7 Financial Models - 4.7 Assess Your Understanding - Page 347: 49

Answer

The continuous compounding at the rate of $5.6\%$ does not yield the required amount. The other bank offers a better deal.

Work Step by Step

The formula for the amount $A$ after $t$ years due to a principal $P$ invested at an annual interest rate $r$ compounded $n$ times per year can be computed as: $A=P(1+\dfrac{r}{n})^{nt}$ When the compounding is continuous, use the formula $A=Pe^{rt}$ We need to compute with continuous compounding. Thus, we use the formula: $A=Pe^{rt}(1)$ We are given the information: $r=0.056 ; t=1; P=1000$ Plugging this in yields the amount after $1$ year: $ A=1000e^{(0.056)(1)}=\$ 1057.60,$ This amount is not enough because the required amount is $\$ 1060$. The other bank offers $r=0.059$, compounded $n=12$ times per year: Thus, we have: $A=1000 (1+\dfrac{0.059}{12})^{12}=\$ 1060.62$ So, this is a better deal than the first bank.
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