The mean or average of a number of observations is the sum of the value of all the observations divided by the total number of observations.
Definition: If are n values of a variable X , then the arithmetic mean or simply the mean of these values is denoted and is defined as
Here, the symbol denotes the sum .
In other words, the arithmetic mean of a set of observations is equal to their sum divided by the total number of observations.
Illustration 1: If the heights of 5 persons are 144 cm, 152 cm, 151 cm, 158 cm and 155 cm respectively. Find the mean height.
Solution: To calculate mean we will find the sum of observations and divide it with number of observations
Illustration 2: The mean of 6, 10, X and 12 is 8. Find the value of x.
Solution: Using the definition
So , the value of x is 4.
The mean of five numbers is 27. If one of the numbers is excluded the mean gets reduced by 2. The excluded number is ___________ | |||
Right Option : A | |||
View Explanation |
Mean of a set of observations is the value which ____________________ | |||
Right Option : C | |||
View Explanation |
The mean of 994, 996, 998, 1000 and 1002 is ________________ | |||
Right Option : C | |||
View Explanation |
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