Question

Mean of 100 observations is 40.Later on it was discovered that two observations 40 and 35
were wrongly taken as 30 and 20 respectively. The corrected mean
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Answer 1

Answer:

Total sum of 100 observations =40×100=4000

After removing two wrong observations

Than, new number of observations =100 – 2 =98

And, sum of 98 observations = 4000–(40+35)=3925

After,adding correct numbers 30 and 20

Than,the new number of number = 98+2 =100

And,sum of new mean =3925+30+20=3975

Therefore, correct mean = 3975÷100=39.75