Question

the mean of marks scored by 100 students was found to be 40. Later on, it was discovered that a score of 53 was misread as 83. Find the correct mean.

Answer 1

As the sum of marks of others remain unchanged , let their sum be x . As the mean using 83 was 40 , we have ,

(x +83)/100 = 40

x + 83 = 4000

x = 3917

Now mean using 53 ,

(x +53)/100

(3917+53)/100

39.7.

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