#### description

- Mean , Median , Mode
- Quartile , Inter quartile

#### notes

The three measures of central tendency for ungrouped data are :

The **mean** (or average) of a number of observations is the sum of the values of all the observations divided by the total number of observations.

So, `bar x =

(sum_(i=1)^n x_i)/ n`.

For an ungrouped frequency distribution, it is `bar x = (sum_(i=1)^n f_ix_i)/(sum_(i=1)^n f_i)`

The **median** is that value of the given number of observations, which divides it into exactly two parts.

If n is an odd number, the median = value of the `((n + 1)/2)^(th)` observation.

If n is an even number, median = Mean of the values of the `(n/2)^(th)` and `(n/2 + 1)^(th)` observation.

The **mode** is that value of the observation which occurs most frequently, i.e., an observation with the maximum frequency is called the mode.

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#### Related QuestionsVIEW ALL [86]

Candidates of four schools appear in a mathematics test. The data were as follows:

Schools | No. of candidates |
Average score |

1 | 60 | 75 |

2 | 48 | 80 |

3 | N A | 55 |

4 | 40 | 50 |

If the average score of the candidates of all the four schools is 66, find the number of

candidates that appeared from school 3.

Find the missing value of p for the following distribution whose mean is 12.58.

x | 5 | 8 | 10 | 12 | p | 20 | 25 |

f | 2 | 5 | 8 | 22 | 7 | 4 | 2 |