A curve or a graph of a cummulative frequency is called cumulative frequency curve or give.
Cummulative frequency or give is used for the determination of a median, quartiles, deciles & percentage.
Median: This is a middle term. It is half of a cummulative frequency.
Quartiles:Here, the cummulative frequency is divided into four places.
Deciles: Here, the cummulative frequency is divided into ten places.
Percentiles: Here, the cummulative frequency is divided into hundred places.
Example:1 The frequency distribution of the hundred participant in a high jump competition as shown below.
|Weight||20 – 29||30 – 39||40 – 49||50 – 59||60 – 69||70 – 79|
- Construct the cumulative frequency table
- Draw the cumulative frequency curve
To construct the cumulative frequency curve, you need the class mid-point and the class boundary
|Weight(kg)||Frequency (f)||Class mark (x)||Cum. freq.||Class boundary|
|20 – 29||10||24.5||10||19.5 – 29.5|
|30 – 39||18||34.5||28||29.5 – 39.5|
|40 – 49||22||44.5||50||39.5 – 49.5|
|50 – 59||25||54.5||75||49.5 – 59.5|
|60 – 69||16||64.5||91||59.5 – 69.5|
|70 – 79||9||74.5||100||69.5 – 79.5|
N.B: 1st cumulative frequency is the same as first frequency
last cumulative frequency is the same as total frequency
Cummulative Frequency Curve
Scale: 1cm to 10 unit on cum. freq axis
2cm to 10 unit on class mark axis
Cummulative Frequency Curve slideshow examples
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