Activity	Normal duration (weeks)	Immediate predecessors	# weeks that can be saved by crashing	Extra cost to crash ($/week saved)
A	5	-	na	na
B	7	-	1	$1,000
C	8	A	2	$600
D	9	A,B	3	$1,500
E	10	B	2	$800
F	10	C,D	4	$2,000
G	6	D	2	$1,800
H	8	E	na	na

If we want to reduce the duration of the project by one week with minimal cost, what activity should we crash (shorten by one week)?

If we want to reduce the duration of the project by a second week (after reducing it by one week as in the first question) with minimal additional cost, which activity should we crash (reduce by one week)?

If we want to shorten the project duration by a third week with minimal additional cost, which activity/activities should we crash (shorten by one week)?

What is the minimal total cost (in dollars) to reduce the duration of this project by three weeks?