Decimal Applications: Mean, Median, and Mode

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Decimal Applications Mean, Median, and Mode
Section 5.7
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Measures of Central Tendency
The mean, the median, and the mode are called
measures of central tendency. They describe a set
of data, or a set of numbers, by a single
middle number.
Martin-Gay, Prealgebra, 5ed
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Mean (Average)

• The most common measure of central tendency is
  the mean (sometimes called the arithmetic mean
  or the average).
• The mean (average) of a set of number items is
  the sum of the items divided by the number of
  items.

Martin-Gay, Prealgebra, 5ed
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Finding the Mean

• Find the mean of the following list of numbers.
• 2.5
• 5.1
• 9.5
• 6.8
• 2.5

Continued.
Martin-Gay, Prealgebra, 5ed
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Finding the Mean

• The mean is the average of the numbers
• 2.5
• 5.1
• 9.5
• 6.8
• 2.5

Martin-Gay, Prealgebra, 5ed
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Median

• You may have noticed that a very low number or a
  very high number can affect the mean of a list of
  numbers. Because of this, you may sometimes want
  to use another measure of central tendency,
  called the median.

The median of an ordered set of numbers is the
middle number. If the number of items is even,
the median is the mean (average) of the two
middle numbers.
Martin-Gay, Prealgebra, 5ed
7
Finding the Median

• Find the median of the following list of numbers.
• 2.5
• 5.1
• 9.5
• 6.8
• 2.5

Continued.
Martin-Gay, Prealgebra, 5ed
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Finding the Median

• List the numbers in numerical order
• 2.5
• 2.5
• 5.1
• 6.8
• 9.5

Martin-Gay, Prealgebra, 5ed
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In order to compute the median, the numbers must
first be placed in order.
Martin-Gay, Prealgebra, 5ed
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Mode

• The mode of a set of numbers is the number that
  occurs most often. (It is possible for a set of
  numbers to have more than one mode or to have no
  mode.)

Martin-Gay, Prealgebra, 5ed
11
Finding the Mode

• Find the mode of the following list of numbers.
• 2.5
• 5.1
• 9.5
• 6.8
• 2.5

Continued.
Martin-Gay, Prealgebra, 5ed
12
Finding the Mode

• List the numbers in numerical order
• 2.5
• 5.1
• 9.5
• 6.8
• 2.5

The mode is 2.5.
Martin-Gay, Prealgebra, 5ed
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Dont forget that it is possible for a list of
numbers to have no mode. For example, the list 2,
4, 5, 6, 8, 9 has no mode. There is no number or
numbers that occur more often than the others.
Martin-Gay, Prealgebra, 5ed