Mean of 15 observation was found to be 75.But later on it was discovered that 61 was misread as 16.Find the correct mean.

Hi Dev,

Mean of 15 observation = Sum of 15 observations / 15

Now, incorrect mean = 75

Therefore, Incorrect mean = Incorrect sum / 15

75 = Incorrect Sum / 15

Incorrect Sum = 75 x 15 = 1125

Given, 61 was misread as 16.

So, we remove 16 and add 61

So, Correct Sum = Incorrect sum - 16 + 61

                           = 1125 - 16 + 61 = 1170

Thus, Correct Mean = Correct Sum / 15

                                = 1170/15 = 78