Question 74

The mean of 20 observations was 85, but later it was found that 97 was misread as 79. The correct mean is:

Solution

given that mean of 20 observations is 85

i.e;(sum of observations)/20=85

sum of observations=1700

but given that 97 was mis read as 79

therefore we need to add the value of 97-79=18

(sum of observations+18)/20 = correct mean

sum of observations=1700

therefore,

(1700+18)/20

=>85.9

therefore answer is optionC

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