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4.3 Fitting Linear Models to Data

Scatter diagrams, judging whether a relationship is linear, least-squares regression on a graphing utility, and predicting within and beyond the data range.

Algebra and Trigonometry 2e, 4.3 Fitting Linear Models to Data

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104 exercises

4.3 Exercise 7

According to the data from the table, what temperature can we predict it is if we counted 20 chirps in 15 seconds?

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Finding a Least Squares Regression Line

Find the least squares regression line using the cricket-chirp data in the table.

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Finding a Correlation Coefficient

Calculate the correlation coefficient for cricket-chirp data in the table.

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4.3 Exercise 11

Use the model we created using technology in the example to predict the gas consumption in 2011. Is this an interpolation or an extrapolation?

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4.3 Exercise 12

Describe what it means if there is a model breakdown when using a linear model.

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4.3 Exercise 14

What is extrapolation when using a linear model?

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4.3 Exercise 16

Explain how to interpret the absolute value of a correlation coefficient.

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4.3 Exercise 18

A regression was run to determine whether there is a relationship between the diameter of a tree ( x x , in inches) and the tree’s age ( y y , in years). The results of the regression are given below. Use this to predict the age of a tree with diameter 10 inches.

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4.3 Exercise 26

r=−0.89 r = −0. \text{89}

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4.3 Exercise 28

r=−0.39 r = −0.39

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4.3 Exercise 34

The U.S. import of wine (in hectoliters) for several years is given in the table. Determine whether the trend appears linear. If so, and assuming the trend continues, in what year will imports exceed 12,000 hectoliters?

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4.3 Exercise 36

Use each set of data to calculate the regression line using a calculator or other technology tool, and determine the correlation coefficient to 3 decimal places of accuracy.

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4.3 Exercise 38

Use each set of data to calculate the regression line using a calculator or other technology tool, and determine the correlation coefficient to 3 decimal places of accuracy.

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4.3 Exercise 40

Use each set of data to calculate the regression line using a calculator or other technology tool, and determine the correlation coefficient to 3 decimal places of accuracy.

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4.3 Exercise 42

Use each set of data to calculate the regression line using a calculator or other technology tool, and determine the correlation coefficient to 3 decimal places of accuracy.

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4.3 Exercise 44

Graph f(x)=−2x−10. f \left(x\right) = - 2 x - 10. Pick a set of five ordered pairs using inputs x=−2,1,5,6,9 x = −2 , \text{1} , \text{5} , \text{6} , 9 and use linear regression to verify the function.

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4.3 Exercise 46

Find to the nearest tenth and interpret the x-intercept.

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4.3 Exercise 48

(2500,2000),(2650,2001),(3000,2003),(3500,2006),(4200,2010) \left(\text{25} 00 , 2000\right) , \left(\text{265} 0 , 2001\right) , \left(3000 , 2003\right) , \left(\text{35} 00 , 2006\right) , \left(\text{42} 00 , 2010\right)

Use linear regression to determine a function y, y , where the year depends on the population. Round to three decimal places of accuracy.

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4.3 Exercise 50

(46,250),(48,305),(50,350),(52,390),(54,410). \left(\text{46} , \text{25} 0\right) , \left(\text{48} , \text{3} 05\right) , \left(50 , \text{35} 0\right) , \left(\text{52} , \text{39} 0\right) , \left(\text{54} , \text{41} 0\right) .

Use linear regression to determine a function y, where the profit in thousands of dollars depends on the number of units sold in hundreds.

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4.3 Exercise 52

(46,250),(48,225),(50,205),(52,180),(54,165). \left(\text{46} , \text{25} 0\right) , \left(\text{48} , \text{225}\right) , \left(50 , \text{2} 05\right) , \left(\text{52} , \text{18} 0\right) , \left(\text{54} , \text{165}\right) .

Use linear regression to determine a function y, where the profit in thousands of dollars depends on the number of units sold in hundreds.

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4.3 Exercise 54

Determine whether the algebraic equation is linear. 2x+3y=7 2 x + 3 y = 7

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4.3 Exercise 56

Determine whether the function is increasing or decreasing.

f( x )=7x−2 f \left(x\right) = 7 x - 2

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4.3 Exercise 58

Given each set of information, find a linear equation that satisfies the given conditions, if possible.

Passes through ( 7,5 ) \left(\text{7} , \text{5}\right) and ( 3,17 ) \left(\text{3} , \text{17}\right)

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4.3 Exercise 64

Does the following table represent a linear function? If so, find the linear equation that models the data.

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4.3 Exercise 66

Determine whether the lines given by the equations below are parallel, perpendicular, or neither parallel nor perpendicular:

2x−6y=12 −x+3y=1 \begin{matrix}2 x - 6 y = 12 \\ - x + 3 y = 1\end{matrix}

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4.3 Exercise 68

Find the x- and y- intercepts of the given equation

7x+9y=−63 7 x + 9 y = - 63

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4.3 Exercise 70

Use the descriptions of the pairs of lines to find the slopes of Line 1 and Line 2. Is each pair of lines parallel, perpendicular, or neither?

Line 1: Passes through (5,11) \left(5 , 11\right) and (10,1) \left(10 , 1\right)

Line 2: Passes through (−1,3) \left(−1 , 3\right) and (−5,11) \left(−5 , 11\right)

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4.3 Exercise 72

Use the descriptions of the pairs of lines to find the slopes of Line 1 and Line 2. Is each pair of lines parallel, perpendicular, or neither?

Write an equation for a line perpendicular to f(x)=5x−1 f \left(x\right) = 5 x - 1 and passing through the point (5, 20).

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4.3 Exercise 76

Use the descriptions of the pairs of lines to find the slopes of Line 1 and Line 2. Is each pair of lines parallel, perpendicular, or neither?

A car rental company offers two plans for renting a car.

Plan A: 25 dollars per day and 10 cents per mile

Plan B: 50 dollars per day with free unlimited mileage

How many miles would you need to drive for plan B to save you money?

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4.3 Exercise 78

A town’s population increases at a constant rate. In 2010 the population was 55,000. By 2012 the population had increased to 76,000. If this trend continues, predict the population in 2016.

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4.3 Exercise 80

Find the linear function y, where y depends on x, x , the number of years since 1980.

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4.3 Exercise 82

Consider this scenario: In 2004, a school population was 1,700. By 2012 the population had grown to 2,500.

Assume the population is changing linearly.

  1. ⓐHow much did the population grow between the year 2004 and 2012?
  2. ⓑWhat is the average population growth per year?
  3. ⓒFind an equation for the population, P, of the school t years after 2004.
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4.3 Exercise 84

Consider this scenario: In 2000, the moose population in a park was measured to be 6,500. By 2010, the population was measured to be 12,500. Assume the population continues to change linearly.

What does your model predict the moose population to be in 2020?

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4.3 Exercise 86

If these trends were to continue, what would be the median home value in Pima Central in 2015?

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4.3 Exercise 92

In what year will the percentage exceed 12%?

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4.3 Exercise 94

Based on the set of data given in the table, calculate the regression line using a calculator or other technology tool, and determine the correlation coefficient to three decimal places.

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4.3 Exercise 96

(3,600,2000);(4,000,2001);(4,700,2003);(6,000,2006) \left(\text{3},\text{6} 00 , 2000\right) ; \left(\text{4}, 000 , 2001\right) ; \left(\text{4},\text{7} 00 , 2003\right) ; \left(\text{6}, 000 , 2006\right)

Predict when the population will hit 12,000.

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4.3 Exercise 98

(3,600,2000);(4,000,2001);(4,700,2003);(6,000,2006) \left(\text{3},\text{6} 00 , 2000\right) ; \left(\text{4}, 000 , 2001\right) ; \left(\text{4},\text{7} 00 , 2003\right) ; \left(\text{6}, 000 , 2006\right)

According to the model, what is the population in 2014?

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4.3 Exercise 99

Determine whether the following algebraic equation can be written as a linear function. 2x+3y=7 2 x + 3 y = 7

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4.3 Exercise 101

Determine whether the following function is increasing or decreasing. f( x )=7x+9 f \left(x\right) = 7 x + 9

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4.3 Exercise 103

Find a linear equation, that has an x intercept at (–4, 0) and a y-intercept at (0, –6), if possible.

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4.3 Exercise 107

Does the table represent a linear function? If so, find a linear equation that models the data.

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4.3 Exercise 109

Determine whether the lines given by the equations below are parallel, perpendicular, or neither parallel nor perpendicular.

y= 3 4 x−9 −4x−3y=8 \begin{matrix}y = \frac{3}{4} x - 9 \\ - 4 x - 3 y = 8\end{matrix}

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4.3 Exercise 111

Determine whether the lines given by the equations below are parallel, perpendicular, or neither parallel nor perpendicular.

Find the x- and y-intercepts of the equation 2x+7y=−14. 2 x + 7 y = - 14.

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4.3 Exercise 113

Determine whether the lines given by the equations below are parallel, perpendicular, or neither parallel nor perpendicular.

Write an equation for a line perpendicular to f(x)=4x+3 f \left(x\right) = 4 x + 3 and passing through the point (8,10). \left(8 , 10\right) .

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4.3 Exercise 117

Determine whether the lines given by the equations below are parallel, perpendicular, or neither parallel nor perpendicular.

A car rental company offers two plans for renting a car.

Plan A: $25 per day and $0.10 per mile

Plan B: $40 per day with free unlimited mileage

How many miles would you need to drive for plan B to save you money?

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4.3 Exercise 119

Determine whether the lines given by the equations below are parallel, perpendicular, or neither parallel nor perpendicular.

A town’s population increases at a constant rate. In 2010 the population was 65,000. By 2012 the population had increased to 90,000. Assuming this trend continues, predict the population in 2018.

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4.3 Exercise 127

In what year will the percentage drop below 4%?

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4.3 Exercise 129

(4,500,2000);(4,700,2001);(5,200,2003);(5,800,2006) \left(4 , 500 , 2000\right) ; \left(4 , 700 , 2001\right) ; \left(5 , 200 , 2003\right) ; \left(5 , 800 , 2006\right)

Use linear regression to determine a function y, where the year depends on the population. Round to three decimal places of accuracy.

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4.3 Exercise 131

(4,500,2000);(4,700,2001);(5,200,2003);(5,800,2006) \left(4 , 500 , 2000\right) ; \left(4 , 700 , 2001\right) ; \left(5 , 200 , 2003\right) ; \left(5 , 800 , 2006\right)

What is the correlation coefficient for this model?

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2.4 Exercise 4

According to the data from the table, what temperature can we predict it is if we counted 20 chirps in 15 seconds?

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Finding a Least Squares Regression Line

Find the least squares regression line using the cricket-chirp data in the table.

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Finding a Correlation Coefficient

Calculate the correlation coefficient for cricket-chirp data in the table.

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2.4 Exercise 8

Use the model we created using technology in the example to predict the gas consumption in 2011. Is this an interpolation or an extrapolation?

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2.4 Exercise 9

Describe what it means if there is a model breakdown when using a linear model.

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2.4 Exercise 11

What is extrapolation when using a linear model?

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2.4 Exercise 13

Explain how to interpret the absolute value of a correlation coefficient.

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2.4 Exercise 15

A regression was run to determine whether there is a relationship between the diameter of a tree ( x,x , in inches) and the tree’s age ( y,y , in years). The results of the regression are given below. Use this to predict the age of a tree with diameter 10 inches.

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2.4 Exercise 17

Draw a scatter plot for the data provided. Does the data appear to be linearly related?

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2.4 Exercise 19

Draw a scatter plot for the data provided. Does the data appear to be linearly related?

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2.4 Exercise 21

Draw a scatter plot for the data provided. Does the data appear to be linearly related?

For the following data, draw a scatter plot. If we wanted to know when the temperature would reach 28 °F, would the answer involve interpolation or extrapolation? Eyeball the line and estimate the answer.

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2.4 Exercise 23

r=−0.89r = - 0. \text{89}

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2.4 Exercise 25

r=−0.39r = - 0.39

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2.4 Exercise 31

The U.S. import of wine (in hectoliters) for several years is given in the table. Determine whether the trend appears linear. If so, and assuming the trend continues, in what year will imports exceed 12,000 hectoliters?

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2.4 Exercise 33

Use each set of data to calculate the regression line using a calculator or other technology tool, and determine the correlation coefficient to 3 decimal places of accuracy.

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2.4 Exercise 35

Use each set of data to calculate the regression line using a calculator or other technology tool, and determine the correlation coefficient to 3 decimal places of accuracy.

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2.4 Exercise 37

Use each set of data to calculate the regression line using a calculator or other technology tool, and determine the correlation coefficient to 3 decimal places of accuracy.

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2.4 Exercise 39

Use each set of data to calculate the regression line using a calculator or other technology tool, and determine the correlation coefficient to 3 decimal places of accuracy.

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2.4 Exercise 41

Graph f(x)=−2x−10f \left(x\right) = - 2 x - 10. Pick a set of 5 ordered pairs using inputs x=−2, 1, 5, 6, 9x = −\text{2} , \textrm{ }\text{1} , \textrm{ }\text{5} , \textrm{ }\text{6} , \textrm{ }\text{9} and use linear regression to verify the function.

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2.4 Exercise 43

(46, 1,600),(48, 1,550),(50, 1,505),(52, 1,540),(54, 1,495)\left(\text{46} , \textrm{ }\text{1} , \text{6} 00\right) , \left(\text{48} , \textrm{ }\text{1} , \text{55} 0\right) , \left(\text{5} 0 , \textrm{ }\text{1} , \text{5} 0 \text{5}\right) , \left(\text{52} , \textrm{ }\text{1} , \text{54} 0\right) , \left(\text{54} , \textrm{ }\text{1} , \text{495}\right).

Find to the nearest tenth and interpret the x-intercept.

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2.4 Exercise 45

(2500, 2000), (2650, 2001), (3000, 2003), (3500, 2006), (4200, 2010) (\text{2500},\textrm{ }\text{2000}),\textrm{ }(\text{2650},\textrm{ }\text{2001}),\textrm{ }(\text{3000},\textrm{ }\text{2003}),\textrm{ }(\text{3500},\textrm{ }\text{2006}),\textrm{ }(\text{4200},\textrm{ }\text{2010})

Use linear regression to determine a function y,y , where the year depends on the population. Round to three decimal places of accuracy.

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2.4 Exercise 47

(46, 250),(48, 305),(50, 350),(52, 390),(54, 410)\left(\text{46} , \textrm{ }\text{25} 0\right) , \left(\text{48} , \textrm{ }\text{3} 0 \text{5}\right) , \left(\text{5} 0 , \textrm{ }\text{35} 0\right) , \left(\text{52} , \textrm{ }\text{39} 0\right) , \left(\text{54} , \textrm{ }\text{41} 0\right).

Use linear regression to determine a function y, where the profit in thousands of dollars depends on the number of units sold in hundreds .

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2.4 Exercise 49

(46, 250), (48, 225), (50, 205), (52, 180), (54, 165). (\text{46},\textrm{ }\text{250}),\textrm{ }(\text{48},\textrm{ }\text{225}),\textrm{ }(\text{50},\textrm{ }\text{205}),\textrm{ }(\text{52},\textrm{ }\text{180}),\textrm{ }(\text{54},\textrm{ }\text{165}) .

Use linear regression to determine a function y, where the profit in thousands of dollars depends on the number of units sold in hundreds .

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2.4 Exercise 51

Determine whether the algebraic equation is linear. 2x+3y=72 x + 3 y = 7

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2.4 Exercise 53

Determine whether the function is increasing or decreasing.

f(x)=7x−2f \left(x\right) = 7 x - 2

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2.4 Exercise 55

Given each set of information, find a linear equation that satisfies the given conditions, if possible.

Passes through (7,5)\left(\text{7} , \text{5}\right) and (3,17)\left(\text{3} , \text{17}\right)

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2.4 Exercise 61

Does the following table represent a linear function? If so, find the linear equation that models the data.

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2.4 Exercise 63

Determine whether the lines given by the equations below are parallel, perpendicular, or neither parallel nor perpendicular:

2x−6y=12 −x+3y=1 \begin{matrix}2 x - 6 y = 12 \\ - x + 3 y = 1\end{matrix}

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2.4 Exercise 65

Find the x- and y- intercepts of the given equation

7x+9y=−637 x + 9 y = −63

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2.4 Exercise 67

Use the descriptions of the pairs of lines to find the slopes of Line 1 and Line 2. Is each pair of lines parallel, perpendicular, or neither?

  1. Line 1: Passes through (5,11)\left(5 , 11\right) and (10,1)\left(10 , 1\right)
  2. Line 2: Passes through (−1,3)\left(−1 , 3\right) and (−5,11)\left(−5 , 11\right)
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2.4 Exercise 69

Use the descriptions of the pairs of lines to find the slopes of Line 1 and Line 2. Is each pair of lines parallel, perpendicular, or neither?

Write an equation for a line perpendicular to f(x)=5x−1f \left(x\right) = 5 x - 1 and passing through the point (5, 20).

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2.4 Exercise 73

Use the descriptions of the pairs of lines to find the slopes of Line 1 and Line 2. Is each pair of lines parallel, perpendicular, or neither?

A car rental company offers two plans for renting a car.

  1. Plan A: 25 dollars per day and 10 cents per mile
  2. Plan B: 50 dollars per day with free unlimited mileage

How many miles would you need to drive for plan B to save you money?

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2.4 Exercise 75

A town’s population increases at a constant rate. In 2010 the population was 55,000. By 2012 the population had increased to 76,000. If this trend continues, predict the population in 2016.

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2.4 Exercise 79

Consider this scenario: In 2004, a school population was 1,700. By 2012 the population had grown to 2,500.

Assume the population is changing linearly.

  1. ⓐ How much did the population grow between the year 2004 and 2012?
  2. ⓑ What is the average population growth per year?
  3. ⓒ Find an equation for the population, P, of the school t years after 2004.
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2.4 Exercise 81

Consider this scenario: In 2000, the moose population in a park was measured to be 6,500. By 2010, the population was measured to be 12,500. Assume the population continues to change linearly.

What does your model predict the moose population to be in 2020?

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2.4 Exercise 83

If these trends were to continue, what would be the median home value in Pima Central in 2015?

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2.4 Exercise 89

In what year will the percentage exceed 12%?

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2.4 Exercise 91

Based on the set of data given in the table, calculate the regression line using a calculator or other technology tool, and determine the correlation coefficient to three decimal places.

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2.4 Exercise 93

(3,600, 2000); (4,000, 2001); (4,700, 2003); (6,000, 2006) (\text{3},\text{600},\textrm{ }\text{2000});\textrm{ }(\text{4},\text{000},\textrm{ }\text{2001});\textrm{ }(\text{4},\text{700},\textrm{ }\text{2003});\textrm{ }(\text{6},\text{000},\textrm{ }\text{2006})

Predict when the population will hit 12,000.

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2.4 Exercise 95

(3,600, 2000); (4,000, 2001); (4,700, 2003); (6,000, 2006) (\text{3},\text{600},\textrm{ }\text{2000});\textrm{ }(\text{4},\text{000},\textrm{ }\text{2001});\textrm{ }(\text{4},\text{700},\textrm{ }\text{2003});\textrm{ }(\text{6},\text{000},\textrm{ }\text{2006})

According to the model, what is the population in 2014?

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2.4 Exercise 96

Determine whether the following algebraic equation can be written as a linear function. 2x+3y=72 x + 3 y = 7

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2.4 Exercise 98

Determine whether the following function is increasing or decreasing. f(x)=7x+9f \left(x\right) = 7 x + 9

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2.4 Exercise 100

Given the following set of information, find a linear equation satisfying the conditions, if possible.

x intercept at (–4, 0) and y-intercept at (0, –6)

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2.4 Exercise 104

Does the table represent a linear function? If so, find a linear equation that models the data.

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2.4 Exercise 106

Determine whether the lines given by the equations below are parallel, perpendicular, or neither parallel nor perpendicular:

y= 3 4 x−9 −4x−3y=8 \begin{matrix}\begin{matrix} \\ y = \frac{3}{4} x - 9\end{matrix} \\ - 4 x - 3 y = 8\end{matrix}

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2.4 Exercise 108

Determine whether the lines given by the equations below are parallel, perpendicular, or neither parallel nor perpendicular:

Find the x- and y-intercepts of the equation 2x+7y=−14.2 x + 7 y = - 14.

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2.4 Exercise 110

Determine whether the lines given by the equations below are parallel, perpendicular, or neither parallel nor perpendicular:

Write an equation for a line perpendicular to f(x)=4x+3f \left(x\right) = 4 x + 3 and passing through the point (8,10).\left(8 , 10\right) .

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2.4 Exercise 114

Determine whether the lines given by the equations below are parallel, perpendicular, or neither parallel nor perpendicular:

A car rental company offers two plans for renting a car.

  1. Plan A: $25 per day and $0.10 per mile
  2. Plan B: $40 per day with free unlimited mileage

How many miles would you need to drive for plan B to save you money?

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2.4 Exercise 116

Determine whether the lines given by the equations below are parallel, perpendicular, or neither parallel nor perpendicular:

A town’s population increases at a constant rate. In 2010 the population was 65,000. By 2012 the population had increased to 90,000. Assuming this trend continues, predict the population in 2018.

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2.4 Exercise 118

Find the linear function yy, where yy depends on xx, the number of years since 1980.

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2.4 Exercise 120

In 2004, a school population was 1250. By 2012 the population had dropped to 875. Assume the population is changing linearly.

  1. ⓐ How much did the population drop between the year 2004 and 2012?
  2. ⓑ What is the average population decline per year?
  3. ⓒ Find an equation for the population, P, of the school t years after 2004.
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2.4 Exercise 124

In what year will the percentage drop below 4%?

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2.4 Exercise 126

(4,500, 2000); (4,700, 2001); (5,200, 2003); (5,800, 2006) (\text{4},\text{500},\textrm{ }\text{2000});\textrm{ }(\text{4},\text{700},\textrm{ }\text{2001});\textrm{ }(\text{5},\text{200},\textrm{ }\text{2003});\textrm{ }(\text{5},\text{800},\textrm{ }\text{2006})

Use linear regression to determine a function y, where the year depends on the population. Round to three decimal places of accuracy.

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2.4 Exercise 128

(4,500, 2000); (4,700, 2001); (5,200, 2003); (5,800, 2006) (\text{4},\text{500},\textrm{ }\text{2000});\textrm{ }(\text{4},\text{700},\textrm{ }\text{2001});\textrm{ }(\text{5},\text{200},\textrm{ }\text{2003});\textrm{ }(\text{5},\text{800},\textrm{ }\text{2006})

What is the correlation coefficient for this model?

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Adapted from College Algebra © 2021 Rice University. Licensed under CC BY 4.0. Sources: College Algebra 2e, Algebra and Trigonometry 2e, Precalculus 2e, College Algebra with Corequisite Support 2e. Imported at revision 4922e46.