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Mathematics

Cummulative Frequency graph

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:The frequency distribution of the hundred participant in a high jump competition as shown below.

Weight20 – 2930 – 3940 – 4950 – 5960 – 6970 – 79
       
  1. Construct the cumulative frequency table
  2. Draw the cumulative frequency curve

Solution

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 – 291024.51019.5 – 29.5
30 – 391834.52829.5 – 39.5
40 – 492244.55039.5 – 49.5
50 – 592554.57549.5 – 59.5
60 – 691664.59159.5 – 69.5
70 – 79974.510069.5 – 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

 Cummulative Frequency Curve slideshow examples

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