1. Mean

2. The term average is used frequently in everyday life to express an amount that is
typical for a group of people or things.
Example : Rohit gets the following marks in different subjects in an examination.
62, 84, 92, 98, 74
Solution:
To get the average marks scored by him in the examination
we first add up all the marks obtained by him in different subjects.
= 410

3. Divide the sum by the total number of subjects. (i.e. 5)
The average marks scored by Rohit is 410 ÷ 5 = 82.
It does not mean that he scored 82 in every subject. Some of the subject mark
may be below 82 and some subject mark may be above 82.
This number helps us to understand the general level of his academic
achievement and is referred to as mean.

4. The average or arithmetic mean or mean is defined as follows.
∴ Sum of all observation = Mean x Total number of observation

5. Example1: The marks in maths of 10 students are .
65 , 72 , 85 , 35 , 90 , 74 , 84 , 71 , 60 , 54
Find the average marks scored in maths
Solution Given:- Marks of 10 students , Total students =10
To Find:- Average marks scored in maths
We know that
Step1:- Calculate sum of all marks
= 690.
Step2:- Calculate mean
Ans: The average marks scored in maths is 69.

6. Try these The weights of 5 people are
72 kg, 48 kg, 51 kg, 69 kg, 67 kg.
Find the mean of their weights.