Hi I'm not sure how to tell if these two estimators are unbiased. Thank you!

Question 1 1 pts Suppose we have a random sample of size 4 from a population with mean u and variance o. Consider the following two estimators of pi 1 P1 =10 XA #2 = X1+-X2+ -X3 + XA Are the two estimators unbiased for /? Both estimators are unbiased. O j is biased, but #2 is unbiased Both estimators are biased. There is not enough information to determine whether the estimators are unbiased. O ] is unbiased, but ji2 is biased