Final answer:
Bayesian Nash equilibrium in the Cournot duopoly model is achieved when both firms choose the quantities that maximize their expected profits, given the probability distribution of their costs.
Step-by-step explanation:
Bayesian Nash equilibrium in the Cournot duopoly model is achieved when both firms choose the quantities that maximize their expected profits, given the probability distribution of their costs. In this case, Firm 1 and Firm 2 have a 50% chance to have a marginal unit cost of 1, and a 50% chance to have a marginal unit cost of 2. Given this information, the firms will consider their expected profits for each possible combination of quantities, taking into account the market demand function, and choose the quantity that maximizes their expected profit.