Notes with answers - Summit Schools
Notes with answers - Summit Schools
Notes with answers - Summit Schools
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Your <strong>Notes</strong><br />
Be sure that about<br />
the same number<br />
of points lie above<br />
your best-fitting<br />
line as lie below it.<br />
approximatinG a BEst-FittinG LinE<br />
Step 1 Draw a scatter plot of the data .<br />
Step 2 Sketch a line that follows the trend of the<br />
data points.<br />
Step 3 Choose two points that appear to lie on the<br />
line, and estimate their coordinates .<br />
Step 4 Write an equation of the line that passes<br />
through the two points from Step 3. This<br />
equation gives a model for the data.<br />
Example 2 Find a Best-Fitting Line<br />
Football attendance The table gives the number of<br />
people y who attended each of the first seven football<br />
games x of the season. Approximate the best-fitting<br />
line for the data.<br />
x 1 2 3 4 5 6 7<br />
y 722 763 772 826 815 857 897<br />
solution<br />
1. Draw a scatter plot.<br />
950<br />
y<br />
2. Sketch the line that<br />
900<br />
best fits the data.<br />
850<br />
800<br />
3. Choose two points on the<br />
line. For this scatter plot you<br />
750<br />
700<br />
650<br />
might choose (1, 725) and<br />
0<br />
0 1 2 3 4 5 6 7 x<br />
( 2 , 750).<br />
Football game<br />
4. Write an equation of the line. First find the slope using<br />
the two points:<br />
750 2 725 25<br />
m 5 } 5 } 5 25<br />
2 2 1 1<br />
Now use point-slope form. Choose (x1 , y1 ) 5 (1, 725).<br />
y 2 y 1 5 m(x 2 x 1 ) Point-slope form<br />
y 2 725 5 25 (x 2 1 ) Substitute for y 1 , m, and x 1 .<br />
Number of people<br />
y 5 25x 1 700 Solve for y.<br />
44 Lesson 2.7 • Algebra 2 C&S Notetaking Guide Copyright © McDougal Littell/Houghton Mifflin Company
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