In a PERT network, the activity durations are given as to (optimistic), tp (pessimistic) and tm (most likely time). What is the variance of is activity ?

In a PERT network, the activity durations are given as to (optimistic)

1.	In a PERT network, the activity durations are given as to (optimistic), tp (pessimistic) and tm (most likely time). What is the variance of is activity ?
A.	<img src="/_files/images/civil-engineering/upsc-civil-service-exam-questions/61-1564-1.png">
B.	<img src="/_files/images/civil-engineering/upsc-civil-service-exam-questions/61-1564-2.png">
C.	<img src="/_files/images/civil-engineering/upsc-civil-service-exam-questions/61-1564-3.png">
D.	None of the above
Answer» D. None of the above