McGraw-Hill Education GRE 2019

Let’s look at a set of data to understand these concepts:

The test scores for seven students in a class are 72, 90, 72, 83, 81, 63, and 94.

The median refers to the data point that has an equal number of data points greater

than it and less than it. In other words, the median is the middle value in a set

when the data points are listed in increasing order.

To determine the median, list the data points from least to greatest.

Listed in increasing order, the data points in the preceding list will read: 63, 72,

72, 81, 83, 90, 94. Since there are seven data points, the median is the fourth data

point.

63, 72, 72, 81, 83, 90, 94

Bottom 3Top 3

Median

In this case, the middle value is 81.

When the number of terms in a set is even, the median will be the average of the two

middle terms.

What is the median of 2, 8, 10, 11, 12, and 14?

SOLUTION: Since there are six data points, the median will be the average of

the middle two values. In this case, the middle two values are 10 and 11.

To determine the median, find the average of 10 and 11. 10 + 11 2 =^212 = 10.5.

■ The range refers to the positive difference between the largest

and smallest value in a set. In the earlier example, the range is

94 – 63 = 31.

■ The mode is the data point that appears most frequently in a set.

In the earlier example, the mode is 72.

■ The average of a set is the sum of the data points/the number of

data points. Put more simply:

A = NS

where A = average of the set, S = sum of the set, and N = number

of data points in the set.

The average of the set in the earlier example is 72 + 90 + 72 + 83 + 81 + 63 + 94 7 =

555

7 = 79.28.

CHAPTER 12 ■ FROM WORDS TO ALGEBRA 327

04-GRE-Test-2018_313-462.indd 327 12/05/17 12:03 pm