You are trying to get the cheapest airfare that you can. You just found on makemytrip.com that the ticket home will cost $400, and it cannot be refunded or exchanged. You also have the option of buying a ticket for $450, which can be refunded for $350 (and thus costs you $100). The price of tickets is expected to change in one week, and you will have one more chance to buy a ticket. There is a 50% chance that the ticket would cost $300, and a 50% chance that it would cost $600. Assuming you are a rational decision maker, construct a decision tree and determine the best course of action to minimize the expected expense of travel (NOT TRAVELING AT ALL IS NOT A CHOICE!).