If XXX is a discrete random variable where P(X=k)=1nP(X=k) = \frac{1}{n}P(X=k)=n1 for k=1,2,…,nk=1, 2, \dots, nk=1,2,…,n, what is the variance of XXX?
n2−112\frac{n^2-1}{12}12n2−1
n+12\frac{n+1}{2}2n+1
n26\frac{n^2}{6}6n2
n(n+1)12\frac{n(n+1)}{12}12n(n+1)