Operations Management
Using the information contained in the table shown, do each of the
following:
A - 0.2
B A 0.2
C - 0.8
D C 0.6
E B 0.3
F D, E 1.0
G F 0.4
H G 0.3
1. Draw a precedence diagram. (5%)
2. Assuming an eight-hour workday, compute the cycle time needed to obtain a
n output of 400 units per day, and determine number of workstations require
d. (5%)
3. Assign tasks to workstations using this rule: Assign tasks according to greatest
number of following tasks. In case of a tie, use the tiebreaker of assigning the
task with the longest processing time first. (5%)
4. Compute resulting percent idle time and efficiency of the system. (5%)
Q2. (10%) Planners for a company that makes several models of skateboards are about
to prepare the capacity plan that will cover six periods. They have assembled the
following information.
Period 1 2 3 4 5 6 Total
Forecast 200 200 300 400 500 200 1,800
They intend to start with zero inventory on hand in the first period, and their
production rate is 290 units per period. Use overtime at a fixed rate of 20 units per
period as needed. Plan for an ending inventory of zero for period 6. Backorders cannot
exceed 90 units per period. Prepare the capacity plan as below.
[BUS002] Operations Management Dr Eun-Seok Kim
2
Period 1 2 3 4 5 6 Total
Forecast 200 200 300 400 500 200 1,800
Production:
Regular 290 290 290 290 290 290 1,740
Overtime
Inventory:
Beginning
Ending
Backorders
Q3. (10%) Surge Electric uses 4,000 toggle switches a year. Switches are priced as
follows: 1 to 499, 90 pence each; 500 to 999, 85 pence each; and 1,000 more, 80 pence
each. It costs approximately £30 to prepare an order and receive it, and carrying costs
are 40 percent of purchase price per unit on an annual basis. Determine the optimal
order quantity and the total cost.
Q4. (10%) A quality inspector took five samples, each with four observations (n=4), of
the length of time for glue to dry. All values are in minutes. Use this information to
obtain three-sigma (i.e., z=3) control limits for a mean control chart and determine
whether the process is in control or not. It is known from previous experience that the
standard deviation of the process is 0.02 minute.
Observation Sam