Question

Arithmetic mean of n observations is m. if two observations 0 and m are added then new mean will be what

Answer 1

Arithmetic mean of n obseravtions is (sum of n obseravtions)/(n)

 Sum of n obseravtions  = Arithmetic mean * n

  = m *n

Now we will add two more observations 0 and m

Then number of observations become n+2 and

sum of observations =  old sum + 0 + m

  = m*n + 0 +m

  = mn+m = m(n+1)

So new mean will be (sum/number of observations) = m(n+1)/(n+2)