The following table gives the frequency distribution of trees planted by different Housing Societies in a particular locality:

No. of Trees | No. of Housing Societies |

10-15 | 2 |

15-20 | 7 |

20-25 | 9 |

25-30 | 8 |

30-35 | 6 |

35-40 | 4 |

Find the mean number of trees planted by Housing Societies by using ‘Assumed Means Method’

Advertisement Remove all ads

#### Solution

By Assumed Mean Method

No. of trees |
Class mark x |
d_{i}=x_{i}-A |
No of housing societies(fi) |
f_{i}d_{i} |

10-15 | 12.5 | -10 | 2 | -20 |

15-20 | 17.5 | -5 | 7 | -35 |

20-25 |
`22.5toA` |
0 | 9 | 0 |

25-30 | 27.5 | 5 | 8 | 40 |

30-35 | 32.5 | 10 | 6 | 60 |

35-40 | 37.5 | 15 | 4 | 60 |

Total | - | - |
` sumf_i=36` |
`sumf_id_i=105` |

`bar d=(sumf_id_i)/(sumf_i)=105/36=2.916`

Mean = `bar x=A+bard` = 22.5 + 2.916 = 25.42

Therefore the mean number of trees planted by Housing Societies is 25.42.

Concept: Mean of Grouped Data

Is there an error in this question or solution?

Advertisement Remove all ads

#### APPEARS IN

Advertisement Remove all ads

Advertisement Remove all ads