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 507: 50



Work Step by Step

Step 1. Given $T_0=24^\circ F, C=65^\circ F, t=10min, T=30^\circ F$, we use Newton's Law of Cooling $T=C+(T_0-C)e^{kt}$; thus, we have: $30=65+(24-65)e^{10k}$ Step 2. Thus $e^{10k}=\frac{35}{41}\approx0.8537$ which gives $k=\frac{ln(0.8537)}{10}\approx-0.0158$. The model equation is then $T=65-41e^{-0.0158t}$ Step 3. Letting $T=45$, we have $65-41e^{-0.0158t}=45$ and $e^{-0.0158t}=\frac{20}{41}$; thus $t=-\frac{ln(20/41)}{0.0158}\approx45.4min$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.