If a variable takes values 0, 1, 2, …………. n with respective frequencies nC0,nC1,nC2......nCn then the A.M is
n
2nn
n+1
n2
N=∑fi=1+nc1+nc1+.....+ncn=2n
∑fixi=1×0+nc1×nc2×2+....+ncn=n
=n[n−1c0+n−1c1+....n−1cn−1]
=n.2n−1A.M=∑fixiN=n.2n−12n=n2