You are a manager of Circuit Town, which sells X box 2010. The demand of X box 2010 in the holiday season is 200 units with probability 0.8 and 400 units with probability 0.2. You have to make an order from MSFT in advance. You can either purchase 200 units or 400 units. The purchase price is $150 per unit and the retail price is $300 per unit. After the holiday,you dump unsold units to leftover.com with price $50 per unit. Build a decision tree and decide how many units you want to order.