Advertisements
Advertisements
Question
A company has three jobs on hand. Each of these must be processed through two departments, in the order AB where
Department A: Press shop and
Department B: Finishing
The table below gives the number of days required by each job in each department
| Job | I | II | III |
| Department A | 8 | 6 | 5 |
| Department B | 8 | 3 | 4 |
Find the sequence in which the three jobs should be processed so as to take minimum time to finish all the three jobs. Also find idle time for both the departments.
Advertisements
Solution
| Job | I | II | III |
| Department A | 8 | 6 | 5 |
| Department B | 8 | 3 | 4 |
Observe that Min(A, B) = 3, corresponds to job II on depatment B.
∴ Job II is placed last in sequence
| II |
Then the problem reduces to
| Job | I | III |
| Department A | 8 | 5 |
| Department B | 8 | 4 |
Now, Min (A, B) = 4, corresponds to job III on department B.
∴ Job III is placed second in sequence and job I on remaining.
∴ Optimal sequence is
| I | III | II |
Total elapsed time.
| Job | Dept. A | Dept. B | ||
| In | Out | In | Out | |
| I (8, 8) | 0 | 8 | 8 | 16 |
| III (5, 4) | 8 | 13 | 16 | 20 |
| II (6, 3) | 13 | 19 | 20 | 23 |
∴ Total elapsed time = 23 days
Idle time for Department A = 23 – 19 = 4 days
Idle time for Department B = 8 days.
APPEARS IN
RELATED QUESTIONS
A machine operator has to perform two operations, turning and threading on 6 different jobs. The time required to perform these operations (in minutes) for each job is known. Determine the order in which the jobs should be processed in order to minimize the total time required to complete all the jobs. Also find the total processing time and idle times for turning and threading operations.
| Job | 1 | 2 | 3 | 4 | 5 | 6 |
| Time of turning | 3 | 12 | 5 | 2 | 9 | 11 |
| Time for threading | 8 | 10 | 9 | 6 | 3 | 1 |
An insurance company receives three types of policy application bundles daily from its head office for data entry and tiling. The time (in minutes) required for each type for these two operations is given in the following table:
| Policy | 1 | 2 | 3 |
| Data Entry | 90 | 120 | 180 |
| Filing | 140 | 110 | 100 |
Find the sequence that minimizes the total time required to complete the entire task.
There are five jobs, each of which must go through two machines in the order XY. Processing times (in hours) are given below. Determine the sequence for the jobs that will minimize the total elapsed time. Also find the total elapsed time and idle time for each machine.
| Job | A | B | C | D | E |
| Machine X | 10 | 2 | 18 | 6 | 20 |
| Machine Y | 4 | 12 | 14 | 16 | 8 |
Find the sequence that minimizes the total elapsed time to complete the following jobs in the order AB. Find the total elapsed time and idle times for both the machines.
| Job | I | II | III | IV | V | VI | VII |
| Machine A | 7 | 16 | 19 | 10 | 14 | 15 | 5 |
| Machine B | 12 | 14 | 14 | 10 | 16 | 5 | 7 |
Find the optimal sequence that minimizes total time required to complete the following jobs in the order ABC. The processing times are given in hours.
| Jobs | I | II | III | IV | V | VI | VII |
| Machine A | 6 | 7 | 5 | 11 | 6 | 7 | 12 |
| Machine B | 4 | 3 | 2 | 5 | 1 | 5 | 3 |
| Machine C | 3 | 8 | 7 | 4 | 9 | 8 | 7 |
Choose the correct alternative :
The objective of sequencing problem is
Choose the correct alternative :
In solving 2 machine and n jobs sequencing problem, the following assumption is wrong
Choose the correct alternative :
In a 3 machine and 5 jobs problem, the least of processing times on machine A, B and C are 5, 1 and 3 hours and the highest processing times are 9, 5 and 7 respectively, then it can be converted to a 2 machine problem if order of the machines is:
Fill in the blank :
The time for which a machine j does not have a job to process to the start of job is called _______.
State whether the following is True or False :
In a sequencing problem, the processing times are dependent of order of processing the jobs on machines.
State whether the following is True or False :
In a sequencing problem, a machine can process more than one job at a time.
State whether the following is True or False :
The time involved in moving a job from one machine to another is negligibly small.
Solve the following problem :
A foreman wants to process 4 different jobs on three machines: a shaping machine, a drilling machine and a tapping machine, the sequence of operations being shaping-drilling-tapping. Decide the optimal sequence for the four jobs to minimize the total elapsed time. Also find the total elapsed time and the idle time for every machine.
| Job | Shaping (Minutes) | Drilling (Minutes) | Trapping (Minutes) |
| 1 | 13 | 3 | 18 |
| 2 | 18 | 8 | 4 |
| 3 | 8 | 6 | 13 |
| 4 | 23 | 6 | 8 |
Choose the correct alternative:
| Machine | Job | |||
| A | B | C | D | |
| I | 5 | 6 | 8 | 4 |
| II | 4 | 7 | 9 | 10 |
The optimal sequence for above data is
Choose the correct alternative:
If there are 3 machines A, B and C, conditions for reducing a 3 machine problem to a 2 machine problem with respect to minimum processing time is ______
If there are n jobs and m machines, then there will be _______ sequence of doing jobs.
Choose the correct alternative:
In solving 2 machine and n jobs sequencing problem, the following assumption is wrong
In assignment problem each worker or machine is ______ capable of handling any job
In sequencing problem the time required to transfer a job from one machine to another is ______
State whether the following statement is True or False:
One of the assumptions is made while sequencing n jobs on 2 machines is: two jobs must be loaded at a time on any machine
State whether the following statement is True or False:
In sequencing problem each job once started on any machine must be processed still its completion
State whether the following statement is True or False:
In sequencing problem each machine is of different type
The processing times required for four jobs A, B, C and D on machine M1 are 5, 8, 10 and 7 hours and on machine M2 it requires 7, 4, 3 and 6 hours respectively. The jobs are processed in the order Ml, M2. The sequence that minimises total elapsed time is ______
