你正面临是否购买某种奖券的决策．你知道每张奖券的售价以及该期共发行奖券的总数、奖项和相应的奖金额．在这样的情况下，该决策的类型是什么加入何种信息以后就该决策将变成一个风险性决策
A．确定性决策；各类奖项的数量．
B．风险性决策；不需要加其他信息．
C．不确定性决策；各类奖项的数量．
D．不确定性决策；可能购买该奖券的人数．
参考答案：C
解析：当没有加入各类奖项的数量时，这是一个不确定性决策．在确定性决策中，其后果事件已知且必定发生；在风险性决策中，其后果事件及其发生概率已知；在不确定性决策中，其后果事件及其发生概率等都不能预先知晓．按题中条件，增加信息前由于不能确定中奖概率，为不确定决策，因此，只有答案A和B排除．而增加购买奖券的人数这…一信息仍不能计算出中奖概率，使决策变成风险性决策，答案D也排除．增加各类奖项的数量信息，可以确定中奖的概率，使决策成为风险性决策，所以，正确答案为C．
According to a new survey, student safety has become a big problem. Now in many big cities of China, many schools start a new lesson: self-protection. Students like this lesson because there are no exams or boring classes. And they can learn how to save lives and know how to stop danger before it really happens. Lin Li, a teacher from Yantai, gives young students advice on how to deal with danger. If you are in a traffic accident If a car hurts you, you should remember the car number. If it is a bicycle, try to call your parents before you let the rider go. This is because you don’t know how seriously you are hurt. If it is raining hard and there is lightning Don’t stay in high places and stay away from trees. When there is a fire Get away as fast as you can. Put wet things on your body and try to find an exit. Do not take the lift. If someone is drowning If you can’t swim, don’t get into the water. Cry out for help. Remember that danger is never as far away as you think. Take care of yourself at all times! If you are robbed（抢劫） Keep calm. If you cannot cry for help or run away, give the robber your money. Try to remember what the robber looks like and tell the police later.
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