Sat math Essentials

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N U M B E R S A N D O P E R AT I O N S R E V I E W
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6 3

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Broken-Line Graphs
Broken-line graphs illustrate a measurable change over time. If a line is slanted up, it represents an increase whereas
a line sloping down represents a decrease. A flat line indicates no change as time elapses.
Scatterplots illustrate the relationship between two quantitative variables. Typically, the values of the inde-
pendent variables are the 
x
-coordinates, and the values of the dependent variables are the 
y
-coordinates. When
presented with a scatterplot, look for a trend. Is there a line that the points seem to cluster around? For example:
H
S
 GP
A
College GP
A
Increase
Decrease
No Change
Increase
Decrease
Change in Time
Unit of Measure
Comparison of Road Work Funds 
of New York and California
1990–1995
New York
California
KEY
0
10
20
30
40
50
60
70
80
90
1991
1992
1993
1994
1995
Money Spent on New Road Work 
in Millions of Dollars
Year
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N U M B E R S A N D O P E R AT I O N S R E V I E W
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In the previous scatterplot, notice that a “line of best fit” can be created:
Practice Question
Based on the graph above, which of the following statements are true? 
I.
In the first hour, Vanessa sold the most lemonade.
II.
In the second hour, Lupe didn’t sell any lemonade.