Plan from the supplied facts
In the fictional model, a wrong design causes 12 extra hours with probability 0.25; otherwise no rework. An investigation costs 4 hours. Assume perfect information could prevent all of that rework and has no other benefit. This generous ceiling saves at most 0.25×12=3 expected hours.
| Model item | Value | Meaning |
|---|---|---|
| Rework chance × hours | 0.25 × 12 | 3 expected hours at risk |
| Perfect prevention | At most 3 | Upper bound before investigation |
| Investigation | 4 hours | Net ceiling −1 hour saved |
Work through the choice
If even perfect information cannot recover its effort cost in this isolated model, imperfect information cannot do better. Additional benefits would require explicit model expansion.
Can this four-hour investigation have a positive expected effort saving under the given assumptions?
Show the worked answer
No. Best possible net saving is 3−4=−1 hour. This conclusion concerns effort only, not unmodelled quality or consequence.
Material to use in your plan
List avoidable effort per scenario, probability, maximum prevention and investigation effort. Use the ceiling as a screening bound, then add other decision consequences explicitly.