Bob and Sue are trying to determine whether or not to get vaccinated against ClamShell Sickness. If neither of them get vaccinated, the probability of getting sick is 0.05%. If both of them get vaccinated, the probability of getting sick is 0.01%. If only one gets vaccinated, then the person not vaccinated has a 0.03% chance of getting sick, while the person who is vaccinated has a 0.02% chance of being sick.

a. Provide the payoff matrix for this scenario. If this were a simultaneous one shot game - explain the equilibrium/equilibria.

b. Would the outcome change if the scenario were played out sequentially - i.e. Bob gets to choose first and then Sue? Explain.

c. Does this scenario depict a positive externality? Explain.

Graph may be used to solve the problem, many thanks