Cumulative Frequency by 4lc4z0

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									Cumulative Frequency
    How to draw a
 cumulative frequency
        graph
 If the data is jumbled, sort it out
          by using a table
 23, 24, 34, 45,
 56, 23, 57, 41,       Data      Frequency
 37, 65, 17, 26, 35,   10 – 20   2
 44, 33, 48, 19,
 61, 58, 55, 49,       20 – 30   4
 44, 57, 43            30 – 40   5
                       40 – 50   7
You must
                       50 – 60   4
decide sensible
intervals              60 – 70   2
  Complete the third column by adding the
         second column like this:
Data      Frequency Cumulative Frequency
10 – 20       2     2
20 – 30       4     2+4=6
30 – 40       5     2 + 4 + 5 = 11
40 – 50       7     2 + 4 + 5 +7 = 18
50 – 60       4     2 + 4 + 5 +7 + 4 = 22
60 – 70       2     2 + 4 + 5 +7 + 4 + 2 = 24
You don’t have to show working
  Data     Frequency   Cumulative
                       Frequency
 10 – 20      2            2

 20 – 30      4            6

 30 – 40      5           11

 40 – 50      7           18

 50 – 60      4           22

 60 – 70      2           24
   Plot the second number in the data column against the number in the
   cumulative frequency column

 Data       Frequency   Cumulative                          30
                        Frequency




                                     Cunulative Frequency
10 –   20      2            2                               25

               4
20 – 30                     6                               20

30 – 40        5           11                               15                                                 Series1



40 – 50        7           18                               10
50 – 60        4           22
                                                            5
60 – 70        2           24
                                                            0
                                                                 0   10   20   30    40    50   60   70   80

                                                                                    Data
   Plot these numbers
                                Now, join up the points
                       30


                       25
Cumulative Frequency




                       20


                       15                                                 Series1




                       10


                       5


                       0
                            0   10   20   30    40    50   60   70   80
                                               Data
        You can use this to find the
 ¾             middle half
(18)   30


       25


       20


       15
 ½                                                     Upper Q
                                                                      Series1



(12)   10                                               (53)
        5
 ¼
(6)     0
            0     10      20   30   40    50      60     70      80


                Lower Q                  Median
                  (30)                    (42)
This means that the middle half is
 between 30 and 53. Called the
      inter-quartile range.
          53 – 30 = 23
   The Lower Quartile is 30
   Median is 42
   The Upper Quartile is 53

								
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