Question 5. [Marks: 10] a) Write short notes on "Scheduling criteria. [2] b) Consider assigning of 3 operators to 3 machines; consider that operator C cannot be [4] assigned to machine 3 for special reasons. The assignment costs in $ are shown in the Table Q5(b) below: Table Q5(b) Machines 1 Operators A 2 3 3 5 9 B 7 4 2 5 5 8 c) i) Assign 3 operators to 3 machines and also appraise the assignment cost. ii) If a 4th operator is available at assignment costs of 2, 1, 8 $ in machines 1, 2 and 3 respectively and if he is to replace one of the old operators, Examine, if it will be economical to hire 4th operator instead of one of the old 3 operators. In a machine tool workshop four jobs are expected to be processed on four different [4] machines. The jobs are labeled as JB1, JB2, JB3, and JB4, and their corresponding operations processing times on each machine are shown in the following Table Q5(c): Table Q5(c) Job Number Machine P Machine Q Machine R Machine S JB1 58 14 48 JB2 35 10 32 JB3 28 15 17 45 JB4 64 16 12 38 13 18 Estimate the schedule, using the extension of Johnson's rule, the flow shop problem of four jobs through four machines and show them in the Gantt chart