Problem 6-2 A manager wants to assign tasks to workstations as efficiently as possible, and achieve an hourly output of 331/3 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. Work Station                 Tasks                 I II III IV b. In order of greatest positional weight. Work Station                  Tasks                I II III IV c. What is the efficiency? (Round your answer to 2 decimal places. Omit the "%" sign in your response. )   Efficiency %   Problem 6-3 A manager wants to assign tasks to workstations as efficiently as possible, and achieve an hourly output of 4 units. The department uses a working time of 56 minutes per 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. Work Station   Tasks I II III IV b. In order of greatest positional weight. Work Station Tasks I II III IV c. What is the efficiency? (Round your answer to 2 decimal places. Omit the "%" sign in your response. )    Efficiency  %   Problem 6-8 A shop works a 400-minute day. The manager of the shop wants an output of 200 units per day for the assembly line that has the elemental tasks shown in the table. Do the following: Task Immediate Predecessor Task Time (minutes) a - 0.5 b a 1.4 c a 1.2 d a 0.7 e b, c 0.5 f d 1.0 g e 0.4 h g 0.3 i f 0.5 j e, i 0.8 k h, j 0.9 m k 0.3 b. Assign tasks according to the most following tasks rule. Work Station             Following Tasks 1 2 3 4 5 c. Assign tasks according to the greatest positional weight rule. Work Station             Following Tasks I II III IV V d. Compute the balance delay for each rule. Which one yields the better set of assignments in this instance? (Omit the "%" sign in your response.)   Balance delay: both part b and c are  %   Problem 6-18 For the set of tasks given below, do the following: Task Task Time (seconds) Immediate Predecessor A 45 - B 11 A C 9 B D 50 - E 26 D F 11 E G 12 C H 10 C I 9 F, G, H J 10 I 193 Assign tasks to stations for a desired output of 500 units in a 7-hour day to balance the line using the longest operation time heuristic. Break ties with the most following tasks heuristic. Calculate the percentage idle time for the line. Use the actual bottleneck cycle time in your calculation. (Round your percentage of idle time to 2 decimal places. Omit the "%" sign in your response.) Work Station Task I II III IV   Percentage of idle time %   Problem 7-1 An analyst has timed a metal-cutting operation for 50 cycles. The average time per cycle was 10.9 minutes, and the standard deviation was 1.20 minutes for a worker with a performance rating of 139 percen.

1. Problem 6-2
A manager wants to assign tasks to workstations as efficiently
as possible, and achieve an hourly output of 331/3 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.
Work Station
Tasks
I
II
III
IV
b.
In order of greatest positional weight.
Work Station
Tasks
I
II
III

2. IV
c.
What is the efficiency? (Round your answer to 2 decimal places.
Omit the "%" sign in your response. )
Efficiency
%
Problem 6-3
A manager wants to assign tasks to workstations as efficiently
as possible, and achieve an hourly output of 4 units. The
department uses a working time of 56 minutes per 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.
Work Station
Tasks
I
II
III
IV
b.

3. In order of greatest positional weight.
Work Station
Tasks
I
II
III
IV
c.
What is the efficiency? (Round your answer to 2 decimal places.
Omit the "%" sign in your response. )
Efficiency
%
Problem 6-8
A shop works a 400-minute day. The manager of the shop wants
an output of 200 units per day for the assembly line that has the
elemental tasks shown in the table. Do the following:
Task
Immediate
Predecessor
Task Time (minutes)
a
-
0.5
b
a

4. 1.4
c
a
1.2
d
a
0.7
e
b, c
0.5
f
d
1.0
g
e
0.4
h
g
0.3
i
f
0.5
j
e, i
0.8
k
h, j
0.9
m
k
0.3
b.
Assign tasks according to the most following tasks rule.

5. Work Station
Following Tasks
1
2
3
4
5
c.
Assign tasks according to the greatest positional weight rule.
Work Station
Following Tasks
I
II
III
IV
V
d.
Compute the balance delay for each rule. Which one yields the
better set of assignments in this instance? (Omit the "%" sign in
your response.)

6. Balance delay: both part b and c are
%
Problem 6-18
For the set of tasks given below, do the following:
Task
Task Time
(seconds)
Immediate
Predecessor
A
45
-
B
11
A
C
9
B
D
50
-
E
26
D
F
11
E
G
12
C
H
10
C

7. I
9
F, G, H
J
10
I
193
Assign tasks to stations for a desired output of 500 units in a 7-
hour day to balance the line using the longest operation time
heuristic. Break ties with the most following tasks heuristic.
Calculate the percentage idle time for the line. Use the actual
bottleneck cycle time in your calculation. (Round your
percentage of idle time to 2 decimal places. Omit the "%" sign
in your response.)
Work Station
Task
I
II
III
IV

8. Percentage of idle time
%
Problem 7-1
An analyst has timed a metal-cutting operation for 50 cycles.
The average time per cycle was 10.9 minutes, and the standard
deviation was 1.20 minutes for a worker with a performance
rating of 139 percent. Assume an allowance of 16 percent of job
time. Find the standard time for this operation. (Do not round
intermediate calculations. Round your final answer to 2
decimal places.)
Standard time
minutes
Problem 7-4
Given these observed times (in minutes) for four elements of a
job, determine the observed time (OT) for each element. Note:
The second element only occurs every other cycle. (Round your
answers to 2 decimal places.)
CYCLE
Element
1
2
3
4
5
6
1
4.1
4.0

9. 4.4
4.1
4.1
4.1
2
-
1.5
-
1.8
-
1.4
3
3.2
3.2
3.6
3.2
3.3
3.3
4
2.7
4.1
2.7
2.8
2.8
2.8
Element
Observed Time
1
2
3
4

10. Problem 7-5
Given these observed times (in minutes) for five elements of a
job, determine the observed time (OT) for each element. Note:
Some of the elements occur only periodically. (Round your
answers to 2 decimal places.)
CYCLE
Element
1
2
3
4
5
6
1
2.1
2.0
2.6
2.1
2.1
-
2
-

11. 1.7
-
1.0
-
1.2
3
3.4
3.5
3.3
3.8
3.4
3.3
4
4.0
-
-
5.1
-
-
5
1.4
1.4
2.0
1.5
1.5
1.4
Element
Observed Time
1
2
3

12. 4
5
Problem 7-6
Using the following data, develop an allowance percentage for a
job element that requires the worker to lift a weight of 30
pounds while (1) standing in a slightly awkward position, (2) in
light that is very inadequate standards, and (3) with intermittent
very loud noises occurring. The monotony for this element is
low. Include a personal allowance of 5 percent and a basic
fatigue allowance of 4 percent of job time. (Leave no cells
blank - be certain to enter "0" wherever required. Omit the "%"
sign in your response.)

13. Percent
Percent
A.
Constant allowances:
4. Bad light:
1. Personal allowance
5
a. Slightly below recommended
0
2. Basic fatigue allowances
4
b. Well below
2
B.
Variable allowances:
c. Very inadequate
5
1. Standing allowance
2
5. Atmospheric conditions
2. Abnormal position allowance:
(heat and humidity)—variable
0-10

14. a. Slightly awkward
0
6. Close attention:
b. Awkward (bending)
2
a. Fairly fine work
0
c. Very awkward (lying, stretching)
7
b. Fine or exacting
2
3. Use of force or muscular energy
c. Very fine or very exacting
5
(lifting, pulling, or pushing):
7. Noise level:
Weight lifted (in pounds):
a. Continuous
0
5
0
b. Intermittent—loud
2
10

15. 1
c. Intermittent—very loud
5
15
2
d. High-pitched—loud
5
20
3
8. Mental strain:
25
4
a. Fairly complex process
1
30
5
b. Complex or wide span of attention
4
35
7
c. Very complex
8
40
9

16. 9. Monotony:
45
11
a. Low
0
50
13
b. Medium
1
60
17
c. High
4
70
22
10. Tediousness:
a. Rather tedious

17. 0
b. Tedious
2
c. Very tedious
5
Factor
%
Personal
Fatigue
Standing
Lifting
Bad Light
Noise Level
Monotony

18. Total
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Problem 5-8
A manager is trying to decide whether to purchase a certain part
or to have it produced internally. Internal production could use

21. either of two processes. One would entail a variable cost of $17
per unit and an annual fixed cost of $200,000; the other would
entail a variable cost of $14 per unit and an annual fixed cost of
$240,000. Three vendors are willing to provide the part. Vendor
A has a price of $20 per unit for any volume up to its maximum
capacity of 30,000 units. Vendor B has a price of $22 per unit
for demand less than 1,000 units, and $18 per unit for larger
quantities. Vendor C offers a price of $21 per unit for the first
1,000 units, and $19 per unit for additional units.
a.
If the manager anticipates an annual volume of 10,000 units,
which alternative would be best from a cost standpoint? For
20,000 units, which alternative would be best? (Omit the "$"
sign in your response.)
TC for 10,000 units
TC for 20,000 units
Int. 1:
$
Int. 1:
$
Int. 2:
$
Int. 2:
$
Vend A
$
Vend A
$
Vend B
$
Vend B
$

22. Vend C
$
Vend C
$
is the best from a cost standpoint.
is the best from a cost standpoint.
b.
Determine the range for which each alternative is best.
Range
Optimal Choice
1 to 999
1,000 to 59,999
60,000 or more
Problem 5-9
A company manufactures a product using machine cells. Each
cell has a design capacity of 250 units per day and an effective
capacity of 230 units per day. At present, actual output averages
200 units per cell, but the manager estimates that productivity
improvements soon will increase output to 222 units per day.
Annual demand is currently 60,000 units. It is forecasted that
within two years, annual demand will triple. How many cells
should the company plan to acquire to satisfy predicted demand
under these conditions? Assume that no cells currently exist.
Assume 245 workdays per year. (Round up your answer to the
next whole number.)
Cells

23. Problem 5-11
A manager must decide which type of machine to buy, A, B, or
C. Machine costs (per individual machine) are as follows:
Machine
Cost
A
$
50,000
B
$
40,000
C
$
70,000
Product forecasts and processing times on the machines are as
follows:
PROCCESSING TIME PER UNIT (minutes)
Product
Annual
Demand
A
B
C
1
12,000

24. 2
1
2
2
21,000
2
6
3
3
11,000
2
4
5
4
25,000
3
5
2
a.
Assume that only purchasing costs are being considered.
Compute the total processing time required for each machine
type to meet demand, how many of each machine type would be
needed, and the resulting total purchasing cost for each machine
type. The machines will operate 10 hours a day, 230 days a
year. (Enter total processing times as whole numbers. Round up
machine quantities to the next higher whole number. Compute
total purchasing costs using these rounded machine quantities.
Enter the resulting total purchasing cost as a whole number.
Omit the "$" sign.)
Total processing time in minutes per machine:

25. A
B
C
Number of each machine needed and total purchasing cost
A
$
B
$
C
$
b.
Consider this additional information: The machines differ in
terms of hourly operating costs: The A machines have an hourly
operating cost of $13 each, B machines have an hourly
operating cost of $15 each, and C machines have an hourly
operating cost of $15 each. What would be the total cost
associated with each machine option, including both the initial
purchasing cost and the annual operating cost incurred to satisfy
demand? (Use rounded machine quantities from Part a. Do not
round any other intermediate calculations. Round your final
answers to the nearest whole number. Omit the "$" sign.)
Total cost for each machine
A
B

26. C
Problem 5-13
The manager of a car wash must decide whether to have one or
two wash lines. One line will mean a fixed cost of $5,700 a
month, and two lines will mean a fixed cost of $9,690 a month.
Each line would be able to process 15 cars an hour. Variable
costs will be $3 per car, and revenue will be $5.95 per car. The
manager projects an average demand of between 14 and 18 cars
an hour. Would you recommend one or two lines? The car wash
is open 260 hours a month.
Choose line.
Problem 5-14
The following diagram shows a 4-step process that begins with
Operation 1 and ends with Operation 4. The rates shown in each
box represent the effective capacity of that operation.
Determine the capacity of this process.
Capacity
/hr
0 Problem 5-15
The following diagram describes a process that consists of eight
separate operations, with sequential relationships and capacities
(units per hour) as shown.
a.
What is the current capacity of the entire process?

27. Capacity
units per hour
b-1.
If you could increase the capacity of only two operations
through process improvement efforts, which two operations
would you select, how much additional capacity would you
strive for in each of those operations? (Enter your answers as
whole numbers. Enter the lower operation number in the TOP
answer box and the higher operation number in the BOTTOM
answer box.)
Operations
Additional capacity
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