Q. 18

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

Answer :

Calculated mean of marks of 50 students = 39

According to the given mean the sum of these marks will be = 39 ×50 = 1950


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


= 1950 + 43 – 23


= 1993 – 23 = 1970


Correct mean = (correct sum)/50 = 1970/50 = 39.4


So, the correct mean is 39.4


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