The mean and standard deviation of 20 observations are found to be 10 and 2, respectively. On rechecking, it was found that an observation 8 was incorrect.

Calculate the correct mean and standard deviation in each of the following cases:


If wrong item is omitted

It is given in the question that,

Total number of observations (n) = 20


Also, incorrect mean = 20


And, incorrect standard deviation = 2





Thus, incorrect sum of observations = 200


Hence, correct sum of observations = 200 – 8


= 192




= 10.1






Thus,


= 2080 – 64


= 2016





= 2.02


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