Two claimants place calls simultaneously to an insurer's claims call center. the times x and y, in minutes, that elapse before the respective claimants get to speak with call center representatives are independently and identically distributed. the moment generating function of each random variable is 1.52 ), t< calculate the standard deviation of x + y oa) 2.1 13) 3.0 oc)4.5 od) 6.7 oe) 9.0