(Solution) MOS3330 Homework 18

Additional Algo 18-4 Weighted Shortest Processing Time

A small manufacturer currently has five jobs waiting to be processed. Processing times and importance weights (higher weight implies higher importance) of the jobs are shown below.

Job	A	B	C	D	E
Processing time (minutes)	14	35	35	31	23
Weight (importance)	1	2	1	5	2

Using the weighted shortest processing time scheduling approach, what is the average inventory of jobs in the system? Assume that processing of jobs will start immediately.

Note: Round your answer to 2 decimal places.

PA 18-1 (Algo) An architect has five projects to complete…

An architect has five projects to complete. She estimates that three of the projects will require one week to complete and the other two will require three weeks and four weeks. During the time these projects are completed (assume no other projects are worked on during this time.)

What is the architect’s flow rate (projects per week)?

Note: Round your answer to 1 decimal place.

Additional Algo 18-6 Earliest Due Date

A car wash near the mall will wash your car while you are shopping and have it ready when you return. Customers provide the car wash with an estimated return time (due date) and the car wash employees have estimated the time required to complete each car.

Job	A	B	C	D	E	F
Due time (minutes)	175	100	135	120	115	80
Processing time (minutes)	36	48	30	44	20	50

Using the earliest due date scheduling process, what is the average inventory of jobs in the system? Assume that processing of jobs will start immediately.

Note: Do not round intermediate calculations. Round your answer to 2 decimal places.

Additional Algo 18-6 Earliest Due Date

Job	A	B	C	D	E	F
Due time (minutes)	135	160	100	130	145	120
Processing time (minutes)	37	42	35	47	27	49

Using the earliest due date scheduling process, what is the average inventory of jobs in the system? Assume that processing of jobs will start immediately.

Note: Do not round intermediate calculations. Round your answer to 2 decimal places.

Additional Algo 18-2 Integrated Work

At an auto shop, six jobs are currently in queue.

Job	A	B	C	D	E	F
Arrival order	1	2	3	4	5	6
Processing time (minutes)	38	15	33	23	24	36

Using the shortest processing time scheduling approach, what is the average inventory of jobs in the system? Assume that processing of jobs will start immediately.

Note: Round your answer to 2 decimal places.

Solution

A small manufacturer currently has five jobs waiting to be processed. Processing times and importance weights (higher weight implies higher importance) of the jobs are shown below.

Job	A	B	C	D	E
Processing time (minutes)	14	35	35	31	23
Weight (importance)	1	2	1	5	2

Using the weighted shortest processing time scheduling approach, what is the average inventory of jobs in the system? Assume that processing of jobs will start immediately.

Note: Round your answer to 2 decimal places.

The jobs will be completed in the order D, E, A, B, C. The average processing time is (31 + 23 + 14 + 35 + 35 / 5 = 27.6 minutes for a flow rate of 1 / 27.6 = 0.0362 jobs per minute.. The average job spends (31 + 54 + 68 + 103 + 138 / 5 = 78.8 minutes in the system.

Inventory = Flow rate × Flow time = 0.0362 × 78.8 = 2.86 jobs.