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Mean_ Median_ Mode_ and Range

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					Aim # 2: How Can We Find the
Measures of Central Tendency?
               Do Now:
• Create a frequency table from the
  following data
• Temperatures in Brooklyn the last two
  weeks
32,30,42,36,48,42,40,42, 36,34,36,42,42,38
          MEAN
A number that helps
describe a set of data is
an AVERAGE!
      How is the mean of a set of
           numbers found?
• Add all the numbers in the set
  together.
• Divide the sum by the number of
  data items in the set.
• The quotient ( the answer) is the
  mean of the set of numbers.
• Example: 10, 18, 12 and 16
  – Add 10 + 18 + 12 + 16 = 56
  – Divide 56 by 4
  – The mean is 14
                  Median
• Is the number that is in the middle
  of a set of numbers.
• Half the numbers are below the
  median and Half the numbers are
  above the median
    How is the median of a set of
          numbers found?
• Arrange the numbers in the set in order
  from least to greatest.
• The middle number is the median of a set
  of numbers.
• If more than one number is in the middle
  of the set of numbers, the mean of those
  two numbers is the median of the set of
  numbers.
Your grades on five tests:
95, 87, 92, 100, and 85

Put them in order from least to greatest


               85, 87, 92, 95, 100
                           Your median test grade is
                           92 – half the time you
  The middle number
                           score below 92 and half
  is the median
                           the time below 92
Your grades on six tests:
95, 87, 92, 100, 85 and 94
Put them in order from least to greatest

                         


          85, 87, 92,        94, 95, 100

                    The median is the mean of 92 and 94

 The middle is                        Or
 between 2                      92 + 94 = 186
 numbers
                             186 divided by 2 = 93
              Remember
• When the order from least to greatest has
  an odd number, there will be one median.
• If the amount of numbers are even, there
  will be two middle numbers that you have
  to add and divide by two to get your
  median.
                   Mode
The number in a data set that occurs most often

Your grades: 95, 87, 85, 100, 100
Your mode is 100


Most of the time you get a 100
How do I identify the mode of a set
           of numbers?

• Arrange the set of numbers in order from
  least to greatest.

• The number that occurs the most often is
  the mode of that set of numbers.
You don’t have to have a
mode…….
Some data sets have no
mode or no number that
occurs more than others
Some might have two
modes
Another    Asks the
way to     Question:
describe   How spread out
data       is my data?
     How is the range of a set of
        numbers identified?

• Arrange the numbers in the set in order
  from least to greatest.

• Subtract the lowest number from the
  highest number in the set of numbers.

• The difference of the two numbers is the
  range of a set of numbers.
Back to your test Scores:
95, 87, 92, 100, and 94

Your highest score is a 100
Your lowest score is 87
Your range is 100 – 87 = 13
The range = 13
    It’s Time To Practice!
Number of pets owned by 7 students:
2, 1, 1, 4, 3, 2, 1
 What is the mean     2

 What is the median   2

 What is the Mode     1

 What is the Range    3
       4 ways to describe data
The Mean – what we usually think of as
the average…..
The Median – The middle number in a
data set…..50% of the numbers are above and
50% are below the median
The Mode – The number that occurs
most often…..
The Range – the difference between the
smallest and bigest number…..

				
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posted:9/1/2012
language:English
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