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 - Chapter Summary, Review, and Test - Review Exercises - Page 481: 34

Answer

See below:

Work Step by Step

(a) The line cuts the \[y\]-axis at the point,\[\left( 0,254 \right)\]. So, the \[y\]-intercept is,\[254\]. The y-intercept of the graph interprets that if none of the adult females are literate then the mortality rate of children under five would be \[254\] per thousand. (b) The slope of a line passing through two points \[\left( {{x}_{1}},{{y}_{1}} \right)\] and \[\left( {{x}_{2}},{{y}_{2}} \right)\] can be calculated by formula change in \[y\] axis divided by change in \[x\] axis as, \[\frac{\Delta y}{\Delta x}=\frac{254-110}{0-60}=-2.4\] The slope of the graph interprets that for each \[1%\] of adult females who are literate corresponding to which the mortality rate of children under \[5\] decreases by \[2.4\]per thousand. Hence, the slope is \[-2.4\] and it describes that for each \[1%\] of adult females who are literate corresponding to which the mortality rate of children under \[5\] decreases by \[2.4\]per thousand. (c) As from part (a) the \[y\]-intercept is \[254\] and from part (b) the slope is \[-2.4\]. Use the equation use of\[y=mx+c\], where \[m\]is the slope and \[c\] is the \[y\]-intercept to determine the equation of the graph by substituting the values of slope and \[y\]-intercept in the slope-intercept equation. Thus, \[f\left( x \right)=y=-2.4x+254\] Hence, the linear function of the provided graph is, \[f\left( x \right)=-2.4x+254\]. (d) Use the function from part (c) that is \[f\left( x \right)=-2.4x+254\], that models child mortality, f(x), per thousand, for children under five in a country where \[x%\] of adult women are literate. For\[x=50\] \[\begin{align} & f\left( 50 \right)=-2.4\cdot 50+254 \\ & =-120+254 \\ & =134 \end{align}\] The mortality rate of children under five in a country is \[134\] per thousand when\[50%\] of adult females are literate.
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