Question

the mean of 5 number is 18 if one number is excluded, their mean is 16 .find the excluded number

Answer 1

Total no : of observations = 5
Mean = 18
Mean = sum of all observations / total no: of observations
∴ Sum of all observation =  Mean × total no : of observations
= 5 × 18 = 90
If one no : is excluded then there will be only 4 observations.
Assume that the excluded no : is  "y "

Sum of the observations = 90 - y
New mean = 16
Sum of all observation =  Mean × total no : of observations
Sum of all observation  = 16 × 4 = 64
90 - y = 64
- y = 64 - 90 = -26
-y = -26
∴ y = 26

∴The excluded no: is 26

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Answer 2

Answer:

• The excluded number is 26

Given :

• The mean of 5 numbers is 18.

• The one number is excluded their mean is 16.

To find :

• The excluded number =?

Step-by-step explanation:

Since the mean of 5 numbers = Sum of 5 numbers /5

But, the mean = 18 [Given]

∴ 18 = sum of 5 numbers /5

∴ Sum of 5 numbers = 90

Let the excluded number be x.

Then, sum of 4 numbers = 90 - x

The mean of 4 numbers = 90 - x / 4

∴ 16 = 90 - x /4

⟹ 64 = 90 - x

⟹ x = 90 - 64

⟹ x = 26

Hence, The excluded number is 26.