Frequency is the number of times something happens within a particular period.

Cumulative means increasing or growing by accumulation or successive additions.

Cumulative frequency is the total of a frequency and all frequencies so far in a frequency distribution.

**How to calculate cumulative frequency. **

The frequency distribution table below records number of plates with their colours.

Colour of plate | Number (Frequency) |

Red | 12 |

Blue | 8 |

Violet | 15 |

Indigo | 20 |

The first cumulative frequency is the same as the first frequency, as you just add a zero to the frequency.

To calculate cumulative frequency, we add the first frequency to the second frequency, then add the third frequency to the result and the process continues.

Colour of plate | Number (frequency) | Cumulative frequency |

Red | 12 | 12 |

Blue | 8 | 20 |

Violet | 15 | 35 |

Indigo | 20 | 55 |

The cumulative frequency in the last row is the same as the total sum of frequencies.