An activity has a ES of 3 days, LS of 13 days, EF of 9 days and LF of 19 days. What is the duration of this activity ?

a) 3

b) 6

c) 7

d) 10

Given Answer : B

What is the correct formula to use ?

Duration = Early Finish - Early Start  + 1  (Assuming 1 as start of the day)

 = 9 - 3 + 1 = 7

Duration = Early Finish - Early Start          (Assuming 0 as start of the day)