Question

A PERT network consists of 5 activities with the following duration.

Activity	Predecessor	Optimistic time (days)	Most likely time (days)	Pessimistic time (days)
P	-	2	4	6
Q	P	4	5	12
R	P	5	8	11
S	Q	2	5	8
T	R	4	6	14

The variance of the critical path is _______

• A. 2.84
• B. 3.66
• C. 5
• D. 4.22

Answer 1

The correct option is D 4.22

$V_{CP}={\left(\frac{6-2}{6}\right)}^2+{\left(\frac{11-5}{6}\right)}^2+{\left(\frac{14-4}{6}\right)}^2$

$=\frac{1}{36}(16+36+100)=4.22$