Corporate Finance
Review Problems and Solutions for
Chapter 6: Process Selection and Facility Layout
For the following three problems (1, 2, 7), we assume that parallel workstations are not allowed.
1. An assembly line with 17 tasks is to be balanced. The longest task is 2.4 minutes, and the total time for all tasks is 18 minutes. The line will operate for 450 minutes per day.
a. What are the minimum and maximum cycle times?
b. What range of output is theoretically possible for the line?
c. What is the minimum number of workstations needed if the maximum output rate is to be sought?
d. What cycle time will provide an output rate of 125 units per day?
e. What output potential will result if the cycle time is (1) 9 minutes? (2) 15 minutes? Solution:
OT = 450 minutes
a. Minimum cycle time = length of longest task, which is 2.4 minutes.
Maximum cycle time = Σ task times = 18 minutes.
b. Range of output:
450
= 187.5 units
2.4
450
@18 min . :
= 25 units
18
Dx ∑ t 187.5(18)
N=
=
= 7.5, which rounds to 8
OT
450
@ 2.4 min . :
c.
OT
450
Solving for CT, CT =
= 3.6 minutes per cycle
CT
125
e. Potential output:
d.
Output =
(1) CT = 9 min . :
OT 450
=
= 50 units
CT
9
(2) CT = 15 min . :
450
= 30 units
15
2. A manager wants to assign tasks to workstations as efficiently as possible, and achieve an hourly output of 33⅓ units. Assume the shop works a 60-minute hour.
Assign the tasks shown in the accompanying precedence diagram (times are in minutes) to workstations using the following rules:
a. In order of most following tasks. Tiebreaker: greatest positional weight.
b. In order of greatest positional weight.
c. What is the efficiency?
Solution:
Desired output = 33.33 units per hour
Operating time = 60 minutes per hour
CT =
Operating time 60 minutes per hour
=
= 1.80 minutes per unit
Desired output 33.33 units per hour
a.
Task
A
B
C
D
E
F
G
H
Number of following tasks
7
6
2
2
2
1
Chapter 6: Process Selection and Facility Layout
For the following three problems (1, 2, 7), we assume that parallel workstations are not allowed.
1. An assembly line with 17 tasks is to be balanced. The longest task is 2.4 minutes, and the total time for all tasks is 18 minutes. The line will operate for 450 minutes per day.
a. What are the minimum and maximum cycle times?
b. What range of output is theoretically possible for the line?
c. What is the minimum number of workstations needed if the maximum output rate is to be sought?
d. What cycle time will provide an output rate of 125 units per day?
e. What output potential will result if the cycle time is (1) 9 minutes? (2) 15 minutes? Solution:
OT = 450 minutes
a. Minimum cycle time = length of longest task, which is 2.4 minutes.
Maximum cycle time = Σ task times = 18 minutes.
b. Range of output:
450
= 187.5 units
2.4
450
@18 min . :
= 25 units
18
Dx ∑ t 187.5(18)
N=
=
= 7.5, which rounds to 8
OT
450
@ 2.4 min . :
c.
OT
450
Solving for CT, CT =
= 3.6 minutes per cycle
CT
125
e. Potential output:
d.
Output =
(1) CT = 9 min . :
OT 450
=
= 50 units
CT
9
(2) CT = 15 min . :
450
= 30 units
15
2. A manager wants to assign tasks to workstations as efficiently as possible, and achieve an hourly output of 33⅓ units. Assume the shop works a 60-minute hour.
Assign the tasks shown in the accompanying precedence diagram (times are in minutes) to workstations using the following rules:
a. In order of most following tasks. Tiebreaker: greatest positional weight.
b. In order of greatest positional weight.
c. What is the efficiency?
Solution:
Desired output = 33.33 units per hour
Operating time = 60 minutes per hour
CT =
Operating time 60 minutes per hour
=
= 1.80 minutes per unit
Desired output 33.33 units per hour
a.
Task
A
B
C
D
E
F
G
H
Number of following tasks
7
6
2
2
2
1