Mean of 100 observations is found to be 40. At the time of computation two items were wrongly taken as 30 and 27 instead of 3 and 72. Find the correct mean.

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Solution

total/100 = 40

total = 4000

incorrect numbers =30+27 = 57,

correct numbers = 3+72 = 75
corrected total = total - incorrect number + correct number
= 4000 - 57 + 75

= 4018

Hence

Correct mean = total / number

= 4018/100

= 40.18

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Mean of 100 observations is found to be 40. At the time of computation two items were wrongly taken as 30 and 27 instead of 3 and 72. Find the correct mean.

total/100 = 40 total = 4000 incorrect numbers =30+27 = 57, correct numbers = 3+72 = 75 corrected total = total - incorrect number + correct number = 4000 - 57 + 75 = 4018 Hence Correct mean = total / number = 4018/100 = 40.18

total/100 = 40

total = 4000

incorrect numbers =30+27 = 57,

correct numbers = 3+72 = 75
corrected total = total - incorrect number + correct number
= 4000 - 57 + 75

= 4018

Hence

Correct mean = total / number

= 4018/100

= 40.18