College Algebra 7th Edition

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

Chapter 1, Equations and Graphs - Section 1.10 - Modeling Variation - 1.10 Exercises - Page 165: 39


$s\approx 46\ $mi/h

Work Step by Step

Since $D$ varies directly as the square of the speed $s$, we have: $D=ks^{2}$ We are given: $D=150$ and $s=40$, so we have: $150=k(40)^{2}$ $k=0.09375$ Therefore: $D=0.09375s^{2}$ If we plug in $D=200$, we can find $s$: $200=0.09375s^{2}$ $s=\sqrt{200/0.09375}$ $s\approx 46\ $mi/h
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