# The mean of 50 observations was 250. later it was found that the number 152 was wrongly copied as 102 for the computation of means. find the correct mean.

Here, we have

No. of observation, N = 50

Incorrect Mean = 250

Right item = 152

Wrong item = 102

As we know that

Mean = Sum of observation ( X )/ No. of observation

250 = X /50

X = 12,500

Hence sum of observation is 12,500

Now

Correct sum of observation = 12500 - Wrong item + Correct item

= 12500 - 102 + 152

= 12, 550

Now correct Mean

Mean = 12550/ 50

= 251

Hence the correct Mean = 251

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