D1, C8 - Critical Path Analysis

Question 1

What goes in the two columns of a precedence / dependence table

Answer 1

Column 1 - Activity (A, B, …)
Column 2 - Dependence (what the activity depends on)

Question 2

What type of graph can you display a precedence / dependence table on

Answer 2

An activity network

Question 3

What is the node at the start and the node at the end of an activity network called

Answer 3

Start - source node
End - sink node

Question 4

What does it mean if an activity network is an ‘activity on arc’ network

Answer 4

The activities are on the arcs (between nodes) as opposed to ‘activity on node’ networks where the activities take place on the nodes

Question 5

How do you number nodes on an activity network

Answer 5

Number them as they are added to the network (chronological order)

Question 6

What does a dummy activity show

Answer 6

Precedence

Question 7

Do dummy activities incur a cost or time

Answer 7

NO

Question 8

When do you get dummy activities

Answer 8

When an activity (C) is dependent on just one other activity (A), but another activity (D) is dependent on the same activity as C (A) but also another activity (B)

Question 9

How do you draw dummy activity lines

Answer 9

Dotted lines

Question 10

What is the time it takes to complete an activity called

Answer 10

Its duration

Question 11

What is an early event time

Answer 11

The earliest time an activity can start / finish

Question 12

What is a late event time

Answer 12

The latest time an activity can start / finish

Question 13

How do you show early and late times on an activity network

Answer 13

Replace nodes with two boxes, top box is the early event time, bottom box is the late event time

Question 14

What numbers go in the early and late time box for the source node

Answer 14

0, 0

Question 15

What numbers go in the early and late time box for the sink node

Answer 15

The SAME number

Question 16

How do you find the early event time

Answer 16

Perform a forward pass/scan
Longest time to finish

Question 17

How do you find the late event time

Answer 17

Perform a backward pass/scan
Shortest time to start

Question 18

For a forward pass do you pick the highest or lowest option

Answer 18

Highest

Question 19

For a backward pass do you pick the highest or lowest option

Answer 19

Lowest

Question 20

What is a critical activity

Answer 20

An activity which will delay the finish time of the project if it is delayed

Question 21

What is a critical path

Answer 21

A path which goes from the source node to the sink node only through critical activities

Question 22

What is true of the early event time and late event times for a critical activity

Answer 22

They are equal
Early event time = late event time

Question 23

Where do critical activities often (not always) happen between

Answer 23

Between critical events

Question 24

Can you have multiple critical paths

Answer 24

YES

Question 25

What is the float of an activity

Answer 25

The amount of time that the start of the activity may be delayed by, without delaying the finish time of a project

Question 26

How do you calculate the total float for an activity

Answer 26

Total float = latest finish time - duration - earliest start time

Question 27

What do Gantt (or Cascade) charts show

Answer 27

The activities on a network

Question 28

What do solid rectangles represent on Gantt charts

Answer 28

Activities

Question 29

What do dotted lines represent on Gantt charts

Answer 29

Delays to activities (floats)

Question 30

Where do you put critical activities on a Gantt chart

Answer 30

On the top row

Question 31

What do resource histograms display

Answer 31

The number of workers needed for an activity

Question 32

How many activities can one worker be assigned to on a resource histogram at a time

Answer 32

1 activity at a time

Question 32

When can workers stop their activity on a resource histogram

Answer 32

When they have finished it

Question 33

How long after finishing an activity does it take for a worker to start a new activity on a resource histogram

Answer 33

Immediately available

Question 34

What is levelling with resource histograms

Answer 34

The process of adjusting the start / finish of activities to take into account any constraints on resources

Question 35

What goes in the x and y axis for a resource histogram

Answer 35

y = number of resources needed per activity (workers) x = time needed per activity (days / hours / etc)

Question 36

For scheduling diagrams how many workers are assumed to be required per activity

Answer 36

One worker assumed to be required per activity

Question 37

For scheduling diagrams which worker do you use

Answer 37

The first available worker

Question 38

For scheduling diagrams, if we can choose more than one activity to assign a worker to, which activity do you choose

Answer 38

Choose the activity with the lowest last time

Question 39

What is the formula to calculate the lower bound for the number of workers needed to complete a project by its critical late time

Answer 39

Lower bound = (sum of all activity times) / (critical time of the project) (take the smallest integer >= the answer)