Question 1) You are the Pennsylvania state official who is responsible for controlling crop damage. A localized infestation of medflies has just been detected, threatening the corn crop in the region. You have three tools at your disposal-burning, spraying, and release of sterile males. You can use these options in various combinations and the characteristics of these options are as follows:

• Burning the infested area will kill the medflies. But burning is expensive, it destroys all flora and fauna, and it may destroy some private property as well.
• You can spray the infested area with pesticide to get rid of medflies. If you spray, you will learn in one month whether or not the spray has eradicated the pest. If the spray fails, you can burn the infested area or spay again. However, burning will cost more this time since a larger area will be infested in one month (see the table below). If, after one month you learn that spray has failed, you can spray a second time. You will learn whether the second spraying eradicates the pest in one month after you undertake it. Again, if the second spray fails again, you must burn the infested area, which costs much now since two months has passed.
• Another alternative is that you can raise a crop of sterile males during the waiting period of the first spray; this takes one month. If the initial spray fails, you can decide to release sterile males and wait for the results for one month or to burn again (spraying is not an option because it will be the same case given above). If a female fly mates with a sterile male, she will have no offspring. You will learn whether sterile males eradicate the fly one month after. Again, if sterile males fail, you must burn the infested area after two months (one month for waiting spray, one month for waiting for sterile males)
• This infestation must be stopped in two months since after this period burning, which is the only sure way of stopping the infestation, is not feasible.

Action	Cost (in millions of dollar)	Probability of success.
Burn Now	60	1
Burn in one month	84	1
Burn in two months	117.6	1
Spray Now	3	1/3
Spray in one month	4.2	1/3
Incubate sterile males for releasing if needed	6
Release sterile males	2	1/2

HINT: These are cost values. Therefore, either enter a negative value to the tree or set the optimal path objective to Minimum payoff, (Settings -> Model Setting -> Calculation tab, set the optimum path to Minimum payoff)

1. What is the best course of action(s) in this problem? What is the expected cost of the best action?
2. What is the minimum cost of initial burning (Burn Now) that will make this alternative economical?
3. What is the risk (probability and cost) in the decision of spray+incubate sterile males and then releasing them?