Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 6 - Section 6.8 - Modeling Using Variation - Exercise Set - Page 488: 25

Answer

$607\; pounds$.

Work Step by Step

Step 1:- Translate the statement to form an equation. Let the weight of the men be $W$ and the height be $H$. Because $W$ varies directly by $H^3$ we have: $\Rightarrow W=kH^3$ ...... (1) Step 2:- Substitute the first set of values into the equation to find the value of $k$. The given values are $W=170\; pounds$ and $H=70\; inches$. Substitute into the equation (1). $\Rightarrow 170=k(70)^3$ $\Rightarrow 170=343000k$ Divide both sides by $343000$. $\Rightarrow \frac{170}{343000}=\frac{343000k}{343000}$ Simplify. $\Rightarrow \frac{17}{34300}=k$ Step 3:- Substitute the value of $k$ into the original equation. Substitute $k=\frac{17}{34300}$ into the equation (1). $\Rightarrow W=\frac{17}{34300}H^3$ ...... (2) Step 4:- Solve the equation to find the required value. Substitute $H=107\;inches$ into the equation (2). $\Rightarrow W=\frac{17}{34300}(107)^3$ Simplify. $\Rightarrow W=607.164169069$ Round to the nearest pound. $\Rightarrow W=607\; pounds$ Hence, the weight was $607\; pounds$.
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