This lesson tests your understanding of the core concepts from Module 2: the critical path method, forward and backward pass calculations, total float, free float, float ownership, and schedule compression. Use it to consolidate what you've learned before moving to Module 3.
How to use this review: Attempt each question before revealing the answer. The network diagram exercise at the end (Q8) is best worked through on paper first — draw the network, run the forward and backward pass, and identify the critical path before checking your answer.
Multiple Choice
Select the best answer for each question.
Q1. Which of the following best describes the Critical Path in a CPM schedule?
Q2. In CPM scheduling, Total Float represents:
Q3. If Activity A has a duration of 5 days and starts on Day 1, its Early Finish (EF) using end-of-day convention is:
Q4. In CPM scheduling, activities on the critical path have:
Q5. Which schedule compression technique involves changing Finish-to-Start (FS) logic to Start-to-Start (SS) to allow activities to run in parallel?
Discussion Questions
Q6. Explain the difference between Total Float and Free Float. Give an example of a situation where an activity might have positive total float but zero free float. Why does this distinction matter in practice?
Q7. A project owner argues that float is a project resource that belongs to no one party. A contractor argues that float they created through efficient scheduling belongs to them. What are the implications of each position? How might the contract wording affect the outcome of this dispute?
Q8 — Network Diagram Exercise
A project has five activities with the following logic:
Activity
Duration (days)
Immediate Predecessor(s)
A
4
—
B
5
A
C
3
A
D
2
B
E
7
C
Using a forward and backward pass:
Draw the activity-on-node (AON) network diagram
Identify all paths through the network
Calculate the duration of each path
Identify the critical path
Calculate the Total Float for each activity
▶ Reveal worked answer
Step 1 — Identify the paths:
Path 1: A → B → D4 + 5 + 2 = 11 daysPath 2: A → C → E4 + 3 + 7 = 14 days
Critical path: A → C → E = 14 days
Activities A, C, and E all have zero Total Float. The project duration is 14 days.
Step 2 — Total Float for each activity:
Activity
ES
EF
LS
LF
Total Float
Critical?
A
0
4
0
4
0
✓ Yes
B
4
9
7
12
3
No
C
4
7
4
7
0
✓ Yes
D
9
11
12
14
3
No
E
7
14
7
14
0
✓ Yes
Note: Activities B and D each have 3 days of Total Float. This 3 days is shared between B and D — if B uses all 3 days of float, D has none left (and vice versa). If D were delayed by 4 days, the project would be delayed by 1 day. Activities A, C, and E have zero float and are critical.
Module 2 Complete — Key Concepts Summary
The critical path is the longest path through the network — it determines the minimum project duration
Total Float is the time an activity can slip without delaying the end date; Free Float is the time an activity can slip without delaying its successors
Activities with zero total float are critical — any delay to them delays the project
Float is shared along a path — use it on one activity and you reduce it for all others on the same path
Fast tracking changes FS to SS logic to allow parallel work; crashing adds resources to shorten critical activity durations
Who owns the float depends on contract terms — always check the programme provisions