Two gunmen make two shots at a specific target, one shot each. the probability of hitting the target for the first gunman is 0.9.the probability of hitting the target for the second gunman is 0.3.both shots are independent events. letxbe the number of timesthe first gunman hits the target (xis 0 or 1) andybe thenumber of hits for the second gunman. letz=x−y.1. find the probability mass function for the random variablez2. find the expected valuee[z] and variancev[z].