Other Scheduling Methods - Construction Project Scheduling and Control - page 302

See Figure 11.8.

Figure 11.8 Solution to example 11.1, part 7

Note that if the instruction had said “the probability that the project
will finish more than [rather than at least ] 2 days late, ”it would have
meant Pr ( T S >

34 ) .
8. The probability that the project will finish on day 32 ± 1day . This means
that the project will finish on day 31, 32, or 33.

Pr ( T s = 31 , 32 , 33 )= Pr ( 30 < T s ≤ 33 )− Pr ( T s ≥ 33 ) Pr ( T s ≤ 30 )

and

Pr ( T s = 31 , 32 , 33 )= 0 . 633 − 0 . 251 = 0 . 382 = 38 . 2 %

See Figure 11.9.

Figure 11.9 Solution to example 11.1, part 8