Suppose there are n people who are faced with the decision of whether to help someone in need of assistance. Each simultaneously choose between helping the victim (help) and ignoring the victim (ignore). Assume that people are like minded. Each person cares about whether the victim is helped, but helping is personally costly. Person is payos can take four possible values, as shown in the table below:

Other PlayersChoices

All other ignore At least one other helps i

's choices Helps 6 4

Ignores 2 12

1. If n = 2; nd out a Nash equilibrium in mixed strategies. Please show the intermediate steps.

2. For n = 2; 3; 4 and 5; nd out the probabilities that the victim will be ignored by everybody. Present your answer in a tabular form (that is, present your answers in a table). Please show the intermediate steps.

3. When n ! 1; nd out the probability that the victim will be ignored by everybody. Please show the intermediate steps.

4. For the victim, does the probability of receiving help go up or down, as n increases? Intuitively explain your answer.