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Statistics is a branch of mathematics that deals with the collection, classification and analysis of numerical data.

The table shows the data of marks scored by a student in eight subjects.

Rohan |
52 | 55 | 57 | 59 | 61 | 63 | 65 | 68 |

Representation of this data as dots on the number line:

The data is scattered along the line.

Statistics that signify the extent of the spread of items around the measure of the central tendency is known as dispersion. It is a single number to describe the variability.

To decide the performance, the variability of the extent of the numerical values is necessary, which is called the central dispersion.

**Methods to find central dispersion:**

- Range
- Quartile deviation
- Mean deviation
- Standard deviation

**Range**

The range of a distribution is the difference between the greatest and the least values observed.

Range = Maximum value - Minimum value

Ex: Consider the data of marks scored by Rohan and Dinesh in eight subjects.

Rohan |
52 | 55 | 57 | 59 | 61 | 63 | 65 | 68 |

Dinesh |
29 | 38 | 42 | 58 | 62 | 74 | 83 | 94 |

Range of the marks scored by Rohan = 68 - 52 = 16

Range of the marks scored by Dinesh = 94 - 29 = 65

The important measures of dispersion, which depend upon the deviations of the observations from a central tendency, are mean deviation and standard deviation.

Statistics is a branch of mathematics that deals with the collection, classification and analysis of numerical data.

The table shows the data of marks scored by a student in eight subjects.

Rohan |
52 | 55 | 57 | 59 | 61 | 63 | 65 | 68 |

Representation of this data as dots on the number line:

The data is scattered along the line.

Statistics that signify the extent of the spread of items around the measure of the central tendency is known as dispersion. It is a single number to describe the variability.

To decide the performance, the variability of the extent of the numerical values is necessary, which is called the central dispersion.

**Methods to find central dispersion:**

- Range
- Quartile deviation
- Mean deviation
- Standard deviation

**Range**

The range of a distribution is the difference between the greatest and the least values observed.

Range = Maximum value - Minimum value

Ex: Consider the data of marks scored by Rohan and Dinesh in eight subjects.

Rohan |
52 | 55 | 57 | 59 | 61 | 63 | 65 | 68 |

Dinesh |
29 | 38 | 42 | 58 | 62 | 74 | 83 | 94 |

Range of the marks scored by Rohan = 68 - 52 = 16

Range of the marks scored by Dinesh = 94 - 29 = 65

The important measures of dispersion, which depend upon the deviations of the observations from a central tendency, are mean deviation and standard deviation.