What are the early and late start times for activities C, D, E, and F?
Carrie meticulously calculated the early and late start and finish times for her latest project and recorded them using different colors of sand on a pristine slab of white marble. She used red for late start and late finish times and green for early start and early finish times. Activity durations and their identifiers were written with black sand. She finished her task and had an opportunity to admire her work only briefly before a colleague came by and swept most of it away. Sadly, this was before Carrie could record the numbers on a more permanent medium, so now she turns to you to help.
Activity Predecessor Duration Early Start Early Finish Late Start Late Finish
A - 10
B - 7 11
C A 7
D A 15 14
E B 11 19
F B 10
G D,E 24
H F 24
J C 28
K G,H,J 36
Answer: Activities A is critical and has an early finish of 10, so C and D must both have an early start of 10. In addition, at least one of these two must have a late start of 10 as the critical path goes through A.
D has a late start of 14, so C must be critical, therefore C's late start time is also 10. D has an early finish of 15, so its late finish must be 4 more than its early finish, or 19. D's duration is 5 as the difference of its early start and early finish times.
C has a duration of 7, so it must have early and late finish times of 10 + 7 = 17.
B's early finish is given as 7 and late finish as 11, so E and F's early start must be 7.
E's early finish is given as 11 and late finish as 19. its early start must be 7 from B's early finish, so adding E's slack to the 7 yields a late start for E of 15. E's duration is therefore 4.
F's duration is given as 10. With an early start of 7, the early finish must be 17. With B's late finish of 11, then the late start for F is also 11. FG's late finish is 21 as it is 10 more than its late start.
Activity Pred Duration Early Start Early Finish Late Start Late Finish
A -- 10 0 10 0 10
C A 7 10 17 10 17
D A 5 10 15 14 19
E B 4 7 11 15 19
F B 10 7 17 11 21