10, 15, 10, 7, 13, 15, 7, 13, 10, 10, 7, 12X F374101241321...
12, 10, 15, 10, 7, 13, 15, 12, 7, 13, 10, 10, 12, 7, 12x f374101213215total:Be sure that the total number of measurements taken is equal to the total at the bottom of the frequencydistribution chart.
D
ATA
R
EPRESENTATION AND
I
NTERPRETATION
The GRE will test your ability to analyze graphs and tables. It is important to read each graph or table verycarefully before reading the question. This will help you process the information that is presented. It isextremely important to read all the information presented, paying special attention to headings and units ofmeasure. On the next page is an overview of the types of graphs you will encounter.Circle Graphs or Pie ChartsThis type of graph is representative of a whole and is usually divided into percentages. Each section of thechart represents a portion of the whole, and all of these sections added together will equal 100% of the whole.25%
40%
35%
Bar GraphsBar graphs compare similar things by using different length bars to represent different values. On the GRE,these graphs frequently contain differently shaded bars used to represent different elements. Therefore, it isimportant to pay attention to both the size and shading of the graph.Comparison of Road Work Funds
of New York and California
1990–1995
90
80
70
60
50
KEY
40
New York
30
California
20
10
0
1991
1992
1993
1994
1995
Money Spent on New Road W
ork
in Millions of Dollars
Year
Broken-Line GraphsBroken-line graphs illustrate a measurable change over time. If a line is slanted up, it represents anincrease, whereas a line sloping down represents a decrease. A flat line indicates no change as time elapses.Decrease
Increase
No Change
Unit of Measure
Change in Time
Percentage and ProbabilityPart of data analysis is being able to calculate and apply percentages and probability. Further review and exam-ples of these two concepts are covered further in the following sections.P
ERCENTAGE
P
ROBLEMS
There is one formula that is useful for solving the three types of percentage problems:# %
= 100
When reading a percentage problem, substitute the necessary information into the previous formulabased on the following:■
100 is always written in the denominator of the percentage-sign column.■
If given a percentage, write it in the numerator position of the number column. If you are not given apercentage, then the variable should be placed there.■
The denominator of the number column represents the number that is equal to the whole, or 100%.This number always follows the word ofin a word problem. For example: “ . . . 13 of 20 apples . . . ”■
The numerator of the number column represents the number that is the percent.■
In the formula, the equal sign can be interchanged with the word is.Example:
Finding a percentage of a given number:What number is equal to 40% of 50?# %
x 40
__ = ___
50 100
Solve by cross multiplying.100(x) = (40)(50)100x= 2,0000
,0
x
=2
1
1
x= 20Therefore, 20 is 40% of 50.Example:
Finding a number when a percentage is given:40% of what number is 24?