Question

Five jobs are waiting for processing through two work centers. Their processing time? (in minutes) at each work center is contained in the table below. Each job requires work center Alpha before work center Beta. According to? Johnson's rule, which job should be scheduled first in the? sequence?

job Alpha beta

r	20	10
s	25	35
t	50	20
u	15	35
v	55	75

Answer 1

Step 1    :    The job with the shortest processing time is r, in work center Beta (with a
                    time of 10 minutes).
                    Because it is at the second centre, schedule r last.

- - - -r

  Step 2     :    Job U has the next shortest time(15).
                            Because that time is the first work centre, we should schedule it first and
                            eliminate it from the consideration

U - - -r

Step 3     :    The next shortest time is Job t(20) on the second machine.
                               Therefore, place it at last.

U- - t r

Step4 : The next shortest time is Job s(25) on the first machine.
                               Therefore, place it at begining.

U S - t r

Final Sequence will be

U S V T R

So , Job U will be sequenced first .