A computer repair shop has two work centers. The first center examines the computer to see what is wrong and the second center repairs the computer. Let x1 and x2 be random variables representing the lengths of time in minutes to examine a computer (x1) and to repair a computer (x2). Assume x1 and x2 are independent random variables. Long-term history has shown the following mean and standard deviation for the two work centers: Examine computer, x1 : 1 = 27.2 minutes; 1 = 7.6 minutes Repair computer, x2 : 2 = 90.6 minutes; 2 = 15.5 minutes Let W=x1 +x2 be a random variable representing the total time to examine and repair the computer. There is a flat rate of $1.80 per minute to examine the computer, and if no repairs are ordered, there is an additional $70 service charge. Let L=1.80x1+70. Compute the mean and standard deviation of L. Question 13 options: a) b) c) d) e)