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Grade 910 grade maths

The mean of n observations is X. If the first item is increased by 1, the second by 2 and so on, then the new mean is:
a) X + n
b) X + n/2
c) X + (n+1)/2
d) X + (n-1)/2

Profile image of Sanskar Pathak
10 Years agoGrade 9
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1 Answer

Profile image of Jayakrishna Natarajan
10 Years ago
Since mean of n obs is x, therefore sum of n obs is n*x
therefore acc to condition: n*(n+1)/2 is added to n*x
new mean is [n*x+n*(n+1)/2]/n
this is equal to opt c