Chapter 15 - Statistics

Mean of Raw Data

Let x₁, x₂, x₃ -------------- , x_n be variables of x, then mean is given by

Mean of ungrouped Data

Suppose the observation x₁ occurs f₁ time, x₂ occurs f₂ time, and so on such that then mean is given by

Some times the variable x are very large number, the computation of mean become difficult. Then we choose a number ‘a’ arbitrary, also called as summed mean.

We find the deviation d_i = x_i – a

Some times di’s are found to be divisible by some number h. in this case the compulation is made easier by putting where

Example 1. Find the mean of the following frequency distribution:

Class interval	10-30	30-50	50-70	70-90	90-110
Frequency	90	20	30	20	40

Solution:-

Class interval	fi	xi	fi xi
10-30	90	20	1800
30-50	20	40	800
50-70	30	60	1800
70-90	20	80	1600
90-110	40	100	4000