Correct Answer - Option 2 : 9
Concept:
In CPM:
The standard deviation of critical path:
σcp = \(\sqrt {Sum\;of\;variance\;along\;critical\;path} \)
σcp = \(\sqrt {σ _1^2 + σ _2^2 + \ldots + σ _8^2 + σ _9^2} \)
Where, σ1, σ2, ...., σ8, σ9 are the standard deviation of each activity on the critical path
Calculation:
Given:
σ1, σ2, ...., σ8, σ9 = 3
σcp = \(\sqrt {σ _1^2 + σ _2^2 + \ldots + σ _8^2 + σ _9^2} \)
σcp = \(\sqrt {3^2 + 3^2 + 3^2 + 3^2 + 3^2 + 3^2 + 3^2 + 3^2 + 3^2} \)
σcp = \(\sqrt {9 \times 9} \) = 9
∴ the standard deviation of the critical path is 9.