Question

The mean of 100 observation is 40 .It is found that an observation 53 was misread as 83 .Find the correct mean.

Answer 1

mean = (sum of 100 observations)/100

40 = (sum of 100 observations)/100

40*100 = sum of 100 observations

4000 = sum of 100 observations

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after that, it was found that 53 was misread as 83, 

Now,

sum of correct 100 observations,  


4000 - 83 + 53

= 4000 - 30

= 3970 

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correct mean = (sum of correct 100 obsercations)/100

correct mean = (3970)/100

correct mean  = 39.7 



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I hope this will help you



- by ABHAY

Answer 2

HEYA!!!!

Here is your answer :
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Given,

Mean of 100 observations =40

An observation as read 83 rather than 53

Then new mean =?

Mean = sum of all observations / number of observations

40 = x - 83 + 53 / 100

40 = x - 30/100

40 × 100 = x- 30

4000= x - 30

4030 = x

Sum of all observations = 4030 then mean =

Mean = 4030/100

= 40. 3

HOPE THIS HELPS U...