**Mean of a Grouped Distribution**

The mean of a distribution, where x represents the midpoints, f the frequencies, and n = ∑f , is

=

Example

Listed below is the grouped frequency distribution for the 30 business executives

Find the mean from the grouped frequency distribution.

Interval | Midpoint, x | Frequency, f | Product, xf |

0-4 | 2 | 3 | 6 |

5-9 | 7 | 4 | 28 |

10-14 | 12 | 6 | 72 |

15-19 | 17 | 8 | 136 |

20-24 | 22 | 5 | 110 |

25-29 | 27 | 3 | 81 |

30-34 | 32 | 1 | 32 |

Total 30 | Total 465 |

= 15.5.