For a group of 200 candidates, mean was found to 40 but it was discovered later that the scores of 43 and 35 were misread as 34 and 53 respectively. Then the correct mean is

Explanation

We have, n=200, incorrect mean =40 and incorrect standard devition =15.
Now, incorrect mean =40



`\Rightarrow` `\quad \frac{\text { Incorrect } \sum x_{i}}{200}=40`

`\Rightarrow` `\text { Incorrect } \sum x_{i}=8000`

`\therefore \text { Correct } \sum x_{i}=8000-(34+53)+(43+35)
=8000-87+78=7991`



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