Let X1,…,XnX_1, \dots, X_nX1,…,Xn be i.i.d. N(0,1)N(0, 1)N(0,1). What is the distribution of ∑Xi2\sum X_i^2∑Xi2?
χn2\chi^2_{n}χn2
Gamma(n/2,2)\text{Gamma}(n/2, 2)Gamma(n/2,2)
Both a and b
None of the above