# NCERT Class 11-Math՚S: Exemplar Chapter – 15 Statistics Part 7 (For CBSE, ICSE, IAS, NET, NRA 2022)

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**Question 19**:

The weights of coffee in jars is shown in the following table:

Weight
| Frequency |

200 - 201 | 13 |

201 - 202 | 27 |

202 - 203 | 18 |

203 - 204 | 10 |

204 - 205 | 1 |

205 - 206 | 1 |

Determine variance and standard deviation of the above distribution.

**Answer**:

Given: the weights of coffee in 70 jars

To find: the variance and standard deviation of the distribution

Let us make a table of the given data and append other columns after calculations

Weight (in grams) | Mid Value | Frequency | |

Total |

Here mean,

So the above table with more columns is as shown below,

Weight (in grams) | Mid Value | Frequency | |||

Total |

And we know standard deviation is

Substituting values from above table, we get

And

Hence the variance and standard deviation of the distribution are 1.166g and 1.08 respectively.