Q. 195.0( 1 Vote )

The mean of 100 items was found to be 64. Later on it was discovered that two items were misread as 26 and 9 instead of 36 and 90 respectively. the correct mean is
A. 64.86

B. 65.31

C. 64.91

D. 64.61

Answer :

Given,


No. of items = 100


Mean of them = 64


Incorrect sum of 100 items = 64 × 100 = 6400.


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


= 6400 – (26 + 9) + (36 + 90)


6400 – 35 + 126 = 6491.


Correct mean = 64.91.

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