Thinking Mathematically (6th Edition)

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

Chapter 7 - Algebra: Graphs, Functions, and Linear Systems - 7.4 Linear Inequalities in Two Variables - Exercise Set 7.4 - Page 454: 49

Answer

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Work Step by Step

(a) A number of children be x and adults be y. Total weight of children and adults will be \[50x+150y\]pounds on the elevator. The elevator will be overloaded if weight exceeds 2000 pounds, \[50x+150y>2000\] (b) The y-intercept is \[\begin{align} & 150y>2000 \\ & y>13.33 \end{align}\] The x-intercept is \[\begin{align} & 50x>2000 \\ & x>40 \end{align}\] Connect the points to form a line. Note the dashed line, since 2000 pounds is not included. No more than 40 children or 13 adults can get into the elevator. (c) The graph of the inequality \[50x+150y>2000\] with ordered-pair \[\left( 25,10 \right)\] Select any point in the shaded region to satisfy the inequality The ordered-pair \[\left( 25,10 \right)\] states that there will be 25 children and 10 adults. Applying the values in the inequality, \[\begin{align} & 50x+150y>2000 \\ & 50\left( 25 \right)+150\left( 10 \right)>2000 \\ & 2750>2000 \end{align}\] If there were 25 children and 10 adults to take up an elevator, it would be overloaded.
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