Algebra Chapter 4 Functions And Linear Modeling Worksheet With Answers

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Algebra
Answers
Name _______________________________________
CHAPTER 4
FUNCTIONS AND LINEAR MODELING
Period ______ Date ____________________________
Section 4.7: Lines of Best Fit Using Point-Slope Form
Example 1: The tread depth of a Michelin car tire was measured for different vehicles and different
distances driven. The table below shows x = the distance driven in thousands of miles and y = the tread
depth in millimeters.
a. Make a scatter plot of the
data on graph paper. Label
and scale your axis.
See attached graph
b. Use a ruler to draw the line
of best fit (trend line)
See attached graph
c. Pick two points that fall on
your line (probably not any
of the original given
points). Use these two
points to calculate the
slope m.
( ��, ��. �� ) ������ (����, ��. ��)
��. �� − ��. ��
−��. ��
�� =
=
���� − ��
����
≈ −��. ����
d. Find units of measure for the slope, m, also known as rate of change. Using the context of the
problem, write a short sentence explaining the meaning of the slope in this problem.
−0.13����
meaning a loss of 0.13 mm of tread for every 1000 miles
1 ��ℎ������������ ����������
( �� −
) to write the
e. Substitute the values of the slope and one point into the equation �� −
��
=
��
��
��
��
equation in point-slope form.
Using ( 4,6.8 )
�� − 6.8 = −0.13(�� − 4)
f. Write the equation of this line in slope-intercept form: �� = ���� + ��. This equation gives us a
linear model for the tire tread depth based on the distance the vehicle was driven.
�� = −0.13�� + 7.32
g. What is the y-intercept of your model? Using the context of the problem, write a short sentence
explaining the meaning of the y-intercept in this problem.
7.32 meaning that when the tire is brand new, it will have 7.32 mm of tread
h. Use your linear model to predict the distance a car must be driven to have a remaining tire tread
depth of 1 millimeter.
1 = −0.13�� + 7.32 → �� = 48.6
���������� ���������� 48,600 ���������� ��ℎ�� ���������� �������� ���� ���� 1����.

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