Four automobiles have entered Bubba's Repair Shop for various types of work, ranging from a transmission overhaul to a brake job. The experience level of the mechanics is quite varied, and Bubba would like to minimize the time required to complete all of the jobs. He has estimated the time in minutes for each mechanic to complete each job. Billy can complete job 1 in 400 minutes, job 2 in 90 minutes, job 3 in 60 minutes, and job 4 in 120 minutes. Taylor will finish job 1 in 650 minutes, job 2 in 120 minutes, job 3 in 90 minutes, and job 4 in 180 minutes. Mark will finish job 1 in 480 minutes, job 2 in 120 minutes, job 3 in 80 minutes, and job 4 in 180 minutes. John will complete job 1 in 500 minutes, job 2 in 110 minutes, job 3 in 90 minutes, and job 4 in 150 minutes. Each mechanic should be assigned to just one of these jobs.
Let X, = 1 if person i is assigned to job j where i = 1 for Billy, 2 for Taylor, 3 for
Mark, 4 for John, and j = 1, 2, 3, and 4 for the job number, and . Xi = 0 otherwise.
What is the constraint function to limit Taylor from being assigned to more than one job?
* a. X41 + X42 + X43 + X44 = 1
* b. X11 + X12 + X13 + X14 = 1
О с. X31 + X32 + X33 + X34 = 1
O d. X21 + X22 + X23 + X24 = 1