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VCE 12 General 2023

9.05 Schedule problems and critical paths

Worksheet
Activities and tasks
1

For each activity chart, construct a graph that will represent the chart:

a
ActivityDurationDependencies
A1-
B8A
C1A
D3B,C
E9D
b
ActivityDurationDependencies
A7-
B4-
C5-
D5A,B,C
E4D
F7D
c
ActivityDurationDependencies
A1-
B4-
C3A
D7B
E3-
F5C,D
G5F,E
d
ActivityDurationDependencies
A7-
B2-
C3A,B
D7A,B
E1C
F9D
e
ActivityDurationDependencies
A2-
B7-
C3-
D8A,B,C
E4D
F5D
G7E,F
f
ActivityDurationPredecessor
A3-
B7A
C1A
D4A
E6B,C
F2C,D
2

Consider the given network. Find the following:

a
The dependencies for activity C.
b
The initial activities.
c
The final activities.
d
The activities without dependencies.
3

Consider the given network. Find the following:

a
The dependencies for activity D.
b
The initial activities.
c
The final activities.
d
The activities without dependencies.
4

For each of the following networks, find:

i
The dependencies for activity E.
ii
The initial activities.
iii
The final activities.
iv
The activities without dependencies.
a
b
c
5

For each of the following networks, find:

i
The dependencies for activity F.
ii
The initial activities.
iii
The final activities.
iv
The activities without dependencies.
a
b
6

Consider the given network. Find the following:

a
The dependencies for activity G.
b
The initial activities.
c
The final activities.
d
The activities without dependencies.
7

For each of the following networks, construct an activity chart by listing the duration and direct dependencies for each activity. If an activity has no dependencies, write X.

a
b
c
d
Forward and backward scanning
8

For each of the given networks and corresponding activity tables, construct a table by listing the vertices and the earliest starting time (EST) for each vertex:

a
ActivityDependenciesDuration
A-2
BA1
CA5
DB3
ED7
FC,E5
b
ActivityDependenciesDuration
A-5
B-2
CA,B3
DA,B4
EC5
FC6
GD,E,F7
HG3
9

For each of the following networks and corresponding activity tables, construct a table by listing the vertices, the earliest starting time (EST), and the latest starting time (LST) for each vertex:

a
ActivityDependenciesDuration
A-5
B-6
C-4
DA,B7
EC2
FC3
GD1
HE,F5
IH8
JG,I9
b
ActivityDependenciesDuration
A-5
B-7
C-4
DA2
EC3
FC1
GA9
HB,D,E,F,G6
c
ActivityPredecessorDuration
A-5
B-6
C-4
D-7
EA,B2
FD3
GF1
HC,E5
IC,E,G8
JH9
KI
LJ,K
10

For each of the following networks, construct a table by listing the vertices, the earliest starting time (EST), and the latest starting time (LST) for each vertex:

a
b
c
d
e
Dummy activities
11

Create an activity table for each of the following networks:

a
b
c
12

Draw a network for each of the following activity tables:

a
ActivityDependencies
F-
G-
HF
IH, G
JG
b
ActivityDependencies
A-
BA
CA
DB
EB, C
c
ActivityDependencies
A-
BA
CA
DB, C
EC
FE
GD
HF, G
IH
JI
Critical path
13

Explain the effect of delaying a critical activity on a project network.

14

Determine whether the following would lead to a delay of the deadline of the whole project:

a

Delaying a critical activity.

b

Delaying a non-critical activity by a duration less than its float time.

c

Delaying a non-critical activity by a duration more than its float time.

15

Determine whether the following statements are true about critical paths in networks:

a

There may be multiple critical paths with the same duration through a network.

b

The average duration of all paths on the network is equal to the duration of the critical path.

c

Activities on the critical path may have a non-zero float time.

d

There is only one critical path in every network.

e

The critical path is the shortest path in the network.

f

The critical path is the set of activities that have a negative float.

g

There is no float for any activity along the critical path.

h

Not all networks have a critical path.

i

The critical path is the set of activities that have a positive float.

j

The earliest start and latest start of all activities on the critical path are equivalent.

16

The following networks have the earliest and latest starting times marked at each vertex. Determine the critical path through the network by listing the activities in order:

a
b
17

For each of the following networks:

i

Construct a table by listing all the vertices, the earliest starting time (EST) and latest starting time (LST) for each vertex.

ii

Determine the critical path through the network by listing the activities in order.

iii

Find the duration of the critical path.

a
b
18

Given the following networks and activity tables:

i

Construct a table by listing all the vertices, the earliest starting time (EST) and latest starting time (LST) for each vertex.

ii

Determine the critical path through the network by listing the activities in order.

iii

Find the duration of the critical path.

a
ActivityDependenciesDuration
A-5
BA1
CA6
DA2
EB,C,D4
FE8
b
ActivityDependenciesDuration
A-5
B-4
C-6
DA7
EB2
FD1
GC3
HG5
IE,F,H4
19

Consider the following activity table:

a

Construct a network that represents the information in the activity table.

b

Construct a table by listing all the vertices, the earliest starting time (EST) and latest starting time (LST) for each vertex.

c

Determine a critical path through the network by listing the activities in order.

d

Find the duration of the critical path.

ActivityPredecessorDuration
A-5
B-5
CB8
DC4
EC3
FA1
GD,E,F7
HG8
IG5
JH,I2
Applications
20

In order to insert a window, several activities need to be performed to complete the project. The following table displays the project’s activities and their descriptions, dependencies, and durations:

ActivityDescriptionDependenciesDuration (hours)
A\text{Buy handtools.}-2
B\text{Buy raw material.}-4
C\text{Cut a hole in the wall.}A3
D\text{Mix up cement.}B2
E\text{Lay thin film of cement on the hole's borders.}C, D3
F\text{Insert window frame.}E1
G\text{Insert window.}F1
H\text{Insert sealant and clean smudges.}G2
a

Construct a network that correctly represents the information in the activity table.

b

Construct a table by listing all the vertices, the earliest starting time (EST) and latest starting time (LST) for each vertex.

c

Determine a critical path through the network by listing the activities in order.

d

Find the duration of the critical path.

e

If the sealant arrived one hour after that activity's earliest start time, how would that affect the project finish time?

21

To bake a cake, several steps should be taken. The following activity table details these steps:

ActivityDescriptionDependenciesDuration (minutes)
A\text{Look up recipe.}-15
B\text{Buy ingredients.}A30
C\text{Prepare cooking utensils.}A10
D\text{Preheat oven.}-5
E\text{Mix dry ingredients} \\ \text{(sugar, flour, baking powder, etc).}B, C4
F\text{Mix wet ingredients} \\ \text{(eggs, milk, oil, etc).}B, C6
G\text{Combine both mixtures.}E, F3
H\text{Grease baking pan.}B, C1
I\text{Pour mixture into baking pan.}G, H2
J\text{Insert baking pan into oven.}D, I30
a

Construct a network correctly that represents the information in the activity table.

b

Construct a table by listing all the vertices, the earliest starting time (EST) and latest starting time (LST) for each vertex.

c

Determine a critical path through the network by listing the activities in order.

d

Find the duration of the critical path.

e

If you forgot to preheat the oven at the beginning and instead turned it on after you had poured the mixture into the pan, how would that affect the total time taken to bake the cake?

22

To manufacture a product, the following steps are to be taken:

ActivityDescriptionDependenciesDuration (days)
A\text{Obtain workers.}-7
B\text{Obtain raw materials.}-4
C\text{Obtain design from engineers.}-3
D\text{Train workers to use machines.}A9
E\text{Produce part 1. } B, C, D2
F\text{Produce part 2. } B, C, D1
G\text{Produce part 3. } B, C, D3
H\text{Test parts.}E, F, G4
I\text{Assemble parts.}H2
J\text{Test product.}I3
K\text{Start mass production.}J3
a

Construct a network that correctly represents the information in the activity table.

b

Construct a table by listing all the vertices, the earliest starting time (EST) and latest starting time (LST) for each vertex.

c

Determine a critical path through the network by listing the activities in order.

d

Find the duration of the critical path.

e

If the production of Part 2 was delayed by 1 day, how would that affect the overall production time?

23

At a restaurant, taking the order of and preparing a steak with mushroom sauce and a side of salad goes through several stages before reaching the customer. The following table describes these stages:

ActivityDescriptionDependenciesDuration (minutes)
A\text{Take order.}-5
B\text{Relay order to kitchen.}A2
C\text{Chef 1} \text{ cooks steak.}B9
D\text{Chef 2} \text{ chops vegetables.}B4
E\text{Chef 3} \text{ prepares the sauce.}B4
F\text{Chef 2} \text{ finishes salad.}D3
G\text{Chef 1} \text{ prepares the plate.}C, E, F2
H\text{Waiter takes order to the table.}G2
a

Construct a network correctly that represents the information in the activity table.

b

Construct a table by listing all the vertices, the earliest starting time (EST) and latest starting time (LST) for each vertex.

c

Determine a critical path through the network by listing the activities in order.

d

Find the duration of the critical path.

e

If Chef 2 takes an extra minute chopping up the vegetables, how will that affect the time taken to prepare the meal?

24

The following table describes the steps involved in producing a movie:

ActivityDescriptionDependenciesDuration (days)
A\text{Obtain script from writers.}-5
B\text{Obtain equipment and set.}-10
C\text{Cast and hire actors.}A13
D\text{Hire employees.}A, B9
E\text{Ready costumes and scenes.}D20
F\text{Record scenes.}C, E32
G\text{Edit recordings.}F11
H\text{Combine scenes and finalise movie.}G6
a

Construct a network that correctly represents the information in the activity table.

b

Construct a table by listing all the vertices, the earliest starting time (EST) and latest starting time (LST) for each vertex.

c

Determine a critical path through the network by listing the activities in order.

d

Find the duration of the critical path.

e

If delivering the movie equipment took a few more days than planned, how would that affect the movie production time?

25

The following activity table describes the steps to build a dressing table:

ActivityDescriptionDependenciesDuration (days)
A\text{Obtain wood, handles, junctions}\ldots-7
B\text{Obtain mirror.}-5
C\text{Obtain tools.}-3
D\text{Build frame.}A, C4
E\text{Build drawers.}D2
F\text{Build top.}D2
G\text{Fit top.}F2
H\text{Fit drawers.}E1
I\text{Sand surfaces then polish.}G, H2
J\text{Insert drawer handles.}I2
K\text{Insert mirror.}B, I1
a

Construct a network that represents the activity table.

b

Construct a table by listing all the vertices, the earliest starting time (EST) and latest starting time (LST) for each vertex.

c

Find the critical path by listing the activities in order.

d

Find the duration of the critical path.

e

If the delivery of the mirror took an extra 5 days, how would that affect the project completion time?

26

To start a fire while camping, the following steps should be taken:

ActivityDescriptionDependenciesDuration (minutes)
A\text{Gather logs, twigs, and dried leaves. }-30
B\text{Obtain lighter or matches.}-5
C\text{Pile up the dried leaves at the bottom.}A7
D\text{Cover dried leaves with twigs.}C3
E\text{Place two logs at the side of the pile} \\ \text{and one log across.}D2
F\text{Light up the pile from the bottom. }B, E2
a

Construct a network that correctly represents the information in the activity table.

b

Construct a table by listing all the vertices, the earliest starting time (EST) and latest starting time (LST) for each vertex.

c

Determine a critical path through the network by listing the activities in order.

d

Find the duration of the critical path.

e

If finding a lighter or matches took 15 minutes longer, how would that affect the time taken to start the fire?

27

A company that produces padlocks takes the following steps in their manufacturing process:

ActivityDescriptionDependenciesDuration (minutes)
A\text{Obtaining raw materials.}-2
B\text{Bolt cutting.}A3
C\text{Drilling and cutting the body.}B6
D\text{Machining the barrel.}B5
E\text{Pinning the barrel.}D3
F\text{Groove cutting shackles.}B1
G\text{Bending shackles.}F1
H\text{Inserting shackle into body.}C, E, G1
I\text{Inserting barrel into body.}H2
J\text{Testing key set.}I1
K\text{Packaging}J3
a

Construct a network that correctly represents the information in the activity table.

b

Construct a table by listing all the vertices, the earliest starting time (EST) and latest starting time (LST) for each vertex.

c

Determine a critical path through the network by listing the activities in order.

d

Find the duration of the critical path.

e

If the machine that pins the barrel broke down and took 2 minutes to repair before being operational, how would that affect the time taken to produce a padlock?

Float times
28

Find the float time of the given activity:

29

Given the following networks with the critical path highlighted in red:

i

List all non-critical activities.

ii

List the non-critical activities in order and the float time of each activity.

a
b
c
30

Given the following networks:

i

Determine a critical path through the network by listing the activities in order.

ii

List all non-critical activities.

iii

List the non-critical activities in order and the float time of each activity.

a
b
c
31

Given the following networks:

i

List the earliest starting time (EST) and latest starting time (LST) for each vertex.

ii

Determine a critical path through the network by listing the activities in order.

iii

List all non-critical activities.

iv

List the non-critical activities in order and the float time of each activity.

a
b
c
d
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