#### Question

The Mean of the following distribution is 52 and the frequency of class interval 30-40 is ‘f’. Find ‘f’.

Class Interval |
10-20 | 20-30 | 30-40 | 40-50 | 50-60 | 60-70 | 70-80 |

Frequency | 5 | 3 | f | 7 | 2 | 6 | 13 |

#### Solution

C.I. | Frequency | Mid Value (x) |
fx |

10-20 | 5 | 15 | 75 |

20-30 | 3 | 25 | 75 |

30-40 | f | 35 | 35f |

40-50 | 7 | 45 | 315 |

50-60 | 2 | 55 | 110 |

60-70 | 6 | 65 | 390 |

70-80 | 13 | 75 | 975 |

`sumf = 36 + f` | `sum fx = 1940 + 35 f` |

Mean = `(sum fx)/(sum f)`

52 = `(1940 + 35f)/(36 + f)`

`=> 1872 + 52f = 1940 + 35f`

`=> 17f = 68`

`=> f = 4`

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#### APPEARS IN

Solution The Mean of the Following Distribution is 52 and the Frequency of Class Interval 30-40 is ‘F’. Find ‘F’. Concept: Measures of Central Tendency - Mean, Median, Mode for Raw and Arrayed Data.