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# Find the mean deviation about the mean for the data

x_{i } 5 10 15 20 25

f_{i } 7 4 6 3 5

**Solution:**

Let us make the table of given data

x_{i} |
f_{i} |
f_{i} x_{i} |
x_{i} - x |
f_{i} x_{i} - x |

5 | 7 | 35 | 9 | 63 |

10 | 4 | 40 | 4 | 16 |

15 | 6 | 90 | 1 | 6 |

20 | 3 | 60 | 6 | 18 |

25 | 5 | 125 | 11 | 55 |

25 | 350 | 158 |

N = ^{5}∑_{i = 1} f_{i} = 25 and ^{5}∑_{i = 1} f_{i}x_{i} = 350

Therefore,

x = 1/N ^{5}∑_{i = 1} f_{i}x_{i}

= (1/25) × 350

= 14

Mean deviation about the mean

M.D. (x) = ^{8}∑_{i = 1} (|x_{i} - x|)/8

= 1/25 × 158

= 6.32

NCERT Solutions Class 11 Maths Chapter 15 Exercise 15.1 Question 5

## Find the mean deviation about the mean for the data xi 5 10 15 20 25 fi 7 4 6 3 5

**Summary:**

The mean deviation about the mean for the given data is 6.32

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