I am going to fly to San Francisco on December 8^th and return home on December 11^th.My travel agent tells me that I could buy a one-way ticket today for $350 or a round-trip ticket for $660.If I wait until December 1^st to buy, a one-way ticket will cost $370 and a round-trip ticket will cost $730.It is possible that before December 1^st, my aunt (who works for the airline) will be able to obtain a free one-way ticket for me back home. If she cannot get the ticket for free, the one-way ticket will cost $370.The probability that my aunt will obtain the free ticket is 0.3.If I bought a round-trip ticket today and my aunt has obtained a free ticket, I may return "half" of my round-trip to the airline.In this case, my total cost will be $330 plus a $50 penalty.

a) Draw a decision tree for this problem.

b) Use the tree from part a) to determine my best course of action.What should I do, and when?What is the expected cost of my obtaining round-trip transportation to San Francisco?