Let X1, X2, and X3 represent the times necessary to perform three successive repair tasks at a certain service facility. Suppose they are independent, normal rv's with expected values r H, and and variances a2, a22, and 32, respectively. (Round your answers to four decimal places.) USE SALT 2 (a) If = H =3 = 60 and = 2 = 03 = 18, calculate P(T 198) and P(144 To 198). 02 P(T 198) = P(144 T 198) = (b) Using the 's and as given in part (a), calculate both P(54 s X) and P(58 X 62). P(54 X) = P(58 sxs 62) = (c) Using the 's and 's given in part (a), calculate P(-12 X -0.5X2 -0.5X3 6). P(-12 X,-0.5X, -0.5X2 6) = A