Question

The US government has contracted with Raytheon to build its new Peacekeeper 2 ballistic missile. The project has been laid out with durations (in weeks), predecessors, and costs included:

Activity	Normal Time (weeks)	Crashed Time (weeks)	Normal Cost	Crashed Cost	Predecessor(s)
A	8	6	$3,600	$4,250	-
B	4	3	$2,250	$3,500	A
C	12	10	$6,150	$6,650	B

How much would it cost to crash the project by one week?

   

How much would it cost to crash the project by three weeks?
   

How much would it cost to crash the project by five weeks?

Answer 1

Activity	Normal Time (weeks)	Crashed Time (weeks)	Normal Cost	Crashed Cost	Slope^^
A	8	6	$3,600	$4,250	$325
B	4	3	$2,250	$3,500	$1,250
C	12	10	$6,150	$6,650	$250

^{^^} Slope = (Crash cost - Normal cost) / (Normal time - Crash time)

A precedes B and B precedes C. So, there is only one project path A-->B-->C.

How much would it cost to crash the project by one week?

Reduce the duration of 'C' due to the minimum slope.

So, the cost would be $250.

How much would it cost to crash the project by three weeks?

2 weeks of 'C' and 1 week of 'A' (next minimum slope) will be crashed.

So, the cost would be 250*2 + 325 = $825

How much would it cost to crash the project by five weeks?

All three activities are to be crashed to their full limit. So, the cost will be 2*250 + 2*325 + 1*1250 = $2,400