a.請問某甲於第一商银存款之利率為何？（5%)

a. If De Beers charges the monopoly price, what is the monopoly price? How large is the individual consumer surplus that each buyer experiences at this monopoly price? Calculate total consumer surplus by summing (lie individual consumer surpluses. How large is producer surplus? (10%) Suppose that upstart Russian and Asian producers enter the market and the market becomes perfectly competitive.