Question

The mean of 20 observations is 12.5. By error, one observation was noted as - 15 instead of

15. Then the correct mean is
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Answer 1

Step-by-step explanation:

Mean of 20 observation =12.5

Sum of 20 observations =12.5×20

                                         =250

Wrong observation is -15

Correct observation is 15

So, Sum of 20 observation correctly =250+15+15=280

First 15 is to eliminate the wrong observation and the other 15 for adding the correct observation in the data.

Correct mean =20280

                        =14