Notes with answers - Summit Schools
Notes with answers - Summit Schools Notes with answers - Summit Schools
Your Notes Homework Example 3 Identify Direct Variation The table gives sample cell phone bills, showing the total monthly cost and the number of minutes used per month. Tell whether total cost and the number of minutes show direct variation. If so, write an equation relating c and m. Total cost, c (dollars) 35 45 80 15 28 Minutes used, m 100 129 229 43 80 solution Find the ratio of c to m for each data pair. 35 } 100 15 } 43 5 0.35 45 } 129 28 < 0.35 } 5 0.35 30 Checkpoint Complete the following exercise. 3. Tell whether the data (21, 22), (1, 2), (3, 6), (5, 10), (7, 14) show direct variation. If so, write an expression relating x and y. direct variation; y 5 2x 80 < 0.35 } < 0.35 229 The ratio of c to m in each pair is nearly the same , so the data show direct variation . Substituting 0.35 for k in c 5 km gives the direct variation equation c 5 0.35 m, which relates the total cost to number of minutes used. 42 Lesson 2.6 • Algebra 2 C&S Notetaking Guide Copyright © McDougal Littell/Houghton Mifflin Company
2.7 Your Notes Scatter plots and correlation Goal p See correlation in a scatter plot and find a best-fitting line. Vocabulary Scatter plot A graph of a set of data pairs (x, y) used to determine whether there is a relationship between the variables x and y Positive correlation A set of data pairs (x, y) for which as x increases, y tends to increase Negative correlation A set of data pairs (x, y) for which as x increases, y tends to decrease Relatively no correlation A set of data pairs (x, y) for which there is no obvious pattern between x and y Best-fitting line The line that most closely models the data shown in a scatter plot Example 1 Identify Correlation Describe the correlation shown by each plot. a. y b. 1 O 1 x Solution a. The scatter plot shows a negative correlation: as x increases, y decreases . b. The scatter plot shows a positive correlation: as x increases , y also increases . Copyright © McDougal Littell/Houghton Mifflin Company Lesson 2.7 • Algebra 2 C&S Notetaking Guide 43 1 O y 1 x
- Page 1 and 2: 2.1 Your Notes Functions and Their
- Page 3 and 4: Your Notes Homework GraphinG EquaTi
- Page 5 and 6: Your Notes Homework b. g (x) 5 x 2
- Page 7 and 8: Your Notes Example 2 Classify Lines
- Page 9 and 10: Your Notes 2.4 quick Graphs of line
- Page 11 and 12: Your Notes Example 2 Draw Quick Gra
- Page 13 and 14: Your Notes 2.5 writing Equations of
- Page 15 and 16: Your Notes Homework y 2 y 1 5 m(x 2
- Page 17: Your Notes The value of k is called
- Page 21 and 22: Your Notes Homework Example 3 Use a
- Page 23: Point-slope form y 2 1 5 2(x 2 5) C
2.7<br />
Your <strong>Notes</strong><br />
Scatter plots and correlation<br />
Goal p See correlation in a scatter plot and find a<br />
best-fitting line.<br />
Vocabulary<br />
Scatter plot A graph of a set of data pairs (x, y)<br />
used to determine whether there is a relationship<br />
between the variables x and y<br />
Positive correlation A set of data pairs (x, y) for<br />
which as x increases, y tends to increase<br />
Negative correlation A set of data pairs (x, y) for<br />
which as x increases, y tends to decrease<br />
Relatively no correlation A set of data pairs (x, y) for<br />
which there is no obvious pattern between x and y<br />
Best-fitting line The line that most closely models<br />
the data shown in a scatter plot<br />
Example 1 Identify Correlation<br />
Describe the correlation shown by each plot.<br />
a. y<br />
b.<br />
1<br />
O<br />
1<br />
x<br />
Solution<br />
a. The scatter plot shows a negative correlation: as<br />
x increases, y decreases .<br />
b. The scatter plot shows a positive correlation: as<br />
x increases , y also increases .<br />
Copyright © McDougal Littell/Houghton Mifflin Company Lesson 2.7 • Algebra 2 C&S Notetaking Guide 43<br />
1<br />
O<br />
y<br />
1<br />
x
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