QUESTION 3 Let X1, X2, X3, ...; Xn be iid random variables with X; ~ N(U, ") , and define the usual sample mean ie X = 1 n EXi ni=1 X - H We know that if Z = then Z ~ N(0, 1 ) . o / Jn X - H If we now define W = where S comes from the usual estimator of O , ie S = 1 - Ex; - X), then what s/ Jn n - 1 i = 1 distribution does W follow? O a. N(0, 1.5) O b.tn- 1 (ie a t-distribution with n-1 degrees of freedom) O c. N(0, 1) O d.t (ie a t-distribution with n degrees of freedom)