The mean of 25 values was 40 But one value was written as 25 instead of 50 The corrected mean is ........

Quantitative Aptitude (RRB NTPC) Statistics

The mean of 25 values was 40. But one value was written as 25 instead of 50. The corrected mean is

Mean of 25 values = 40

Sum of 25 values = 40 x 25 = 1000

One value was written 25 instead of 50

Correct sum = 1000 – 25 + 50 =1025

New average = 1025/25 = 41

SHORT TRICK :

Difference between values = 50 – 25

New average = 40 + 25/25 = 41

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