6th Grade Math Textbook, Progress

Apply Measures of Central

Tendency and Range

9-5

The mean, median, and mode of a data set are called measures of central tendency.

They indicate where the greatest number of the data set is concentrated. The range

represents the spread between the greatest and the least values of the data set.

Gloria keeps a record of the number

of sit-ups she does each day.

To describe Gloria’s data, you can use

the mean, median, mode, or range.

• The meanof a data set of n
  numbers is the sum of the
  numbers divided by n.
  The mean, 35, shows the number of sit-ups Gloria would do
  each day if the total number of sit-ups were evened out.


• The medianof a data set is the
  middle number when the data
  are arranged in order.
  28 30 30 35 37 40 45

The median, 35, shows that the number of days Gloria did less than 35 sit-ups

equals the number of days she did more than 35.

• The modeof a data set is the number
  that occurs most frequently.
  28, 30 , 30 , 35, 37, 40, 45

The mode, 30, shows that Gloria does 30 sit-ups

more frequently than any other number of sit-ups.

• The rangeis the difference between the 45
  28  17
  greatest and the least values in a data set.
  The range, 17, shows how far the data is spread out from the
  greatest number of sit-ups to the least number of sit-ups.

Day S M T W Th F S

Number of

Sit-ups

28 30 30 37 35 40 45

  35

245

7

28  30  30  37  35  40  45

7

mean

range

median

mode

For an even number of data,

the median is the average

of the two middle numbers.

12, 13 , 14 , 15, median ^13 
 214 13.5

Sometimes a data set has no mode

or has more than one mode.

29, 33, 35, 31, 30, 32 has no mode.

28, 31 , 31 , 29 , 36, 29 , 35 has two

modes: 31 and 29.

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