個經寡占? - 經濟

Roach Motors is the dominant used-car dealer in a small Midwesren city. After
paying $50000 for overhead, Roach Motors' cost per car is $500. There are 4
other small used-cae lots in this town, but since they are not large enough to
purchase cars through the same discount sources as Roach, each firm face the
cost function C=5000+700Q+5Q^2. The demand for used cars is Q=300-P1/10.
Assuming Roach sets the market price so as to maximize its profit, how many
cars will each of the follower firms supply? ANS:13

他說到Roach set the price 然後如果先算Roach 的profit-maximizing
y=125 p=1750 可是如果是他要set price我就不知道怎麼做下去了QQ
如果set產量 還可以用follower的反應函數去算 不過好像也跟答案不太一樣= =

我另外用Cournot duopoly下去算 QR=95 4Qf=60 可是還是跟答案差一點QQ

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