Q18 of 174 Page 597

The mean of the marks scored by 50 students was found to be 39. Later on it was discovered that a score of 43 was misread as 23. The correct mean is

Given,


No. of students = 50


Mean marks secured by them = 39


Incorrect sum of marks secured = 39 × 50 = 1950.


Correct sum = incorrect sum – (incorrect marks) + correct marks


= 1950 – 23 + 43 = 1970


Correct mean = 39.4.

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