Question

Below are the project steps for the creation of a television advertisement for Foolio, which is a new energy drink that the musician Coolio has created. Consider the following data for questions 1 through 5:

Activity	Duration (days)	Description	Preceding Activity(ies)
A	3	Create script for advertisement	-
B	4	Book technical crew	A
C	5	Book actors	A
D	4	Create props and costumes	B,C
E	2	Book location	C
F	6	Filming and editing	D,E

1. How many paths are there through this network?

1. 1
2. 2
3. 3
4. 4

2. How many critical paths are there?

1. 0
2. 1
3. 2
4. 3

3. Which activities have slack?

1. BC
2. BD
3. BE
4. CE

4. What is the slack for activity B?

1. 0
2. 1
3. 2
4. 3

Answer 1

Based on the given data, we prepare a project network diagram as shown below:

The above network diagram in the form of formulas is shown below for better understanding and reference:

The above project diagram is prepared as per legend shown in top-left corner.

EST = Early start time

LST = Late start time

EFT = Early finish time

LFT = Late finish time

SLK = Slack = LST - EST or Slack = LFT - EFT

The EST of an activity = EFT of previous activity

EFT of an activity = EST + Duration

Similarly, LFT & LST are calculated during the backward pass.

There are multiple paths in the diagram:

A-B-D-F

A-C-D-F

A-C-E-F

Hence, there are 3 paths. Out of the above paths, path A-C-D-F is the longest path and has 0 slack. Hence, this is the critical path. Hence there is 1 critical path.

As seen from project network diagram, activity B & E are non-critical and have slack. Hence, 2 activities have slack.

Slack for activity B = 1

We summarize the answers as shown below:

Question 1: How many paths are there through this network?

Answer: c) 3

How many critical paths are there?

Answer: b) 1

Which activities have slack?

Answer: c) BE

What is the slack for activity B?

Answer: b) 1

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