7th Grade Math

GLE 0706.1.2 Apply and adapt a variety of appropriate strategies to problem solving, including estimation,

and reasonableness of the solution. Also addresses GLE 0706.1.5, GLE 0706.3.2, SPI 0706.3.5.

402 Linear Functions

Variation

PART A BCDE

Multi-Part

Lesson 3

Main Idea Solve problems by using a graph.

Use a Graph

RICK: The table shows the study times and test

scores of 13 students in Mrs. Collins’s English

class.

YOUR MISSION: Use a graph to predict the test

score of a student who studied for 80 minutes.

Study Time and Test Scores

Study Time (min) 120 30 60 95 70 55 90 45 75 60 10

Test Score (%) 98 75 80 93 82 78 95 74 87 83 65

Problem-Solving Investigation

Understand You know the number of minutes studied. You need to predict the test score.

Plan Organize the data in a graph so you

can easily see any trends.

Study Time and Test Scores

65

75

85

95

0 20 40 60 80 100

Study Time (min)

Test Score (%)

y

x

Solve As the study times progress, the test

scores increase. Draw a line that is

close to as many of the points as

possible. You can predict that the test

score of a student who studied for

80 minutes is about 88%.

Check The estimate is close to the line, so the

prediction is reasonable.

1. Explain why analyzing a graph is a useful way to quickly make conclusions
   about a set of data.


2. E WRITE MATH Write a real-world problem in which using a graph would
   be a useful way to check a solution.

402_403_C07_PSI_895130.indd 402 12/31/09 4:28 PM