2. [-/13 Points] DETAILS DEVORESTAT9 5.3.038.MI. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER There are two traffic lights on a commuter's route to and from work. Let X, be the number of lights at which the commuter must stop on his way to work, and X2 be the number of lights at which he must stop when returning from work. Suppose that these two variables are independent, each with the pmf given in the accompanying table (so X, , X2 is a random sample of size n = 2). * 1 0 1 2 p(x1) |0.4 0.3 0.3 H = 0.9, 02 = 0.69 (a) Determine the pmf of To = X1 + X2. to 3 p (t ) (b) Calculate UT. HTO How does it relate to u, the population mean? HT = (c) Calculate T 2 2 = How does it relate to of, the population variance? 2 =[ . 02 (d) Let X3 and X4 be the number of lights at which a stop is required when driving to and from work on a second day assumed independent of the first day. With To = the sum of all four X,'s, what now are the values of E(T.) and V(T.)? E(T ) = V( T ) = (e) Referring back to (d), what are the values of P(T. = 8) and P(T, 2 7) [Hint: Don't even think of listing all possible outcomes!] P(T = 8 ) = P ( T 27 ) = Need Help? Read It Watch It Master It