Let 1 A be the indicator of event A. That is, the random variable 1 A takes the value 1 if A occurs and is 0 if A occurs. (a) What is the support of 1A? (b) What is the p.m.f. of 1 A? (c) Compute E[ 1 4]. (d) What should the subscript of the indicator r.v. on the r.h.s. of the fol- lowing equation be so that equality holds? 1 A+1B - 1AB = 17. You may assume that A and B are events. (e) Take the expected value of each side, and you end up with what familiar equation