Thinking Mathematically (6th Edition)

Published by Pearson
ISBN 10: 0321867327
ISBN 13: 978-0-32186-732-2

Chapter 5 - Number Theory and the Real Number System - 5.4 The Irrational Numbers - Exercise Set 5.4 - Page 296: 77


The speed of motorist is 70 mph and the officer should not believe the motorist as he exceeded 20 mph from the speed limit.

Work Step by Step

Substitute $245$ for $L$ in the given formula and calculate $v$. That is., Write $245$ into its prime factors and take square root. That is., $v=2\sqrt{5L}$ $v=2\sqrt{5*245}$ $\begin{align} & v=2\sqrt{5\times 5\times {{7}^{2}}} \\ & =2\times 5\times 7 \\ & =70 \end{align}$ Thus, the speed of motorist was $70\text{ mph}$. Since it is greater than $50\text{ mph}$, he was speeding.
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.