The mean marks of 100 students were found to be 40. Later on it was discovered that a score of 53 was misread as 83. The corrected mean corresponding to the corrected score is
A
37.5
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B
35.6
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C
39.7
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D
38.7
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Solution
The correct option is C39.7 Let the x1,x2,x3........x100 be the marks of 100 student
So,mean ¯x=x1+x2+x3+........+x100100=40x1+x2+x3+........+x100=4000
As we have added 83 instead of 53 so corrected sum is x1+x2+x3+........+x100−83+53=4000−83+53=3970
So,the corrected mean ¯xcorrected=3970100=39.7