Chapter 15 - Statistics

Mean of Raw Data

Let x1, x2, x3 -------------- , xn 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 di = xi – 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
   

 

Maths by Mr. M. P. Keshari
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Subjects Maths (Part-1) by Mr. M. P. Keshari
Chapter 9 Circle
Chapter 10 Tangents to a circle
Chapter 11 Geometrical Construction
Chapter 12 Troigonometry
Chapter 13 Height and Distance
Chapter 14 Mensuration
Chapter 15 Statistics
Chapter 16 Probability
Chapter 17 Co-ordinate Geometry