What is cumulative frequency?
Cumulative frequency represents a value which is equal to the sum of all frequencies upto and including that value. For example, in the tabular data shown
Literacy rate (in %) | Number of cities (cf) | Frequency |
Less than 30 30 − 40 40 − 50 50 − 60 | 2 6 14 20 | 2 4 8 6 |
n = 20 |
Cumulative frequency for interval 40-50 is find out by adding all the frequencies upto mentioned interval as well as including the frequency value of said interval i.e.,
cumulative frequency of 40-50 interval = 2+4+8 = 14