UPSC Civil Service Exam Questions - Engineering

Q1:

The optimistic, most likely and pessimistic time estimates of an activity are 5, 10 and 21 days respectively. What are the expected time and standard deviation respectively ?

A 12, 3

B 11, 4

C 11, 2.67

D 10, 16

ANS:C - 11, 2.67

t = (5 + 10 * 4 + 21)/6 = 11,
sd = (21-5)/6 = 2.67.