# 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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