What makes monopolistic firms stay in production against competition?

You would like to purchase one class a share of berkshire hathaway through your scottrade brokerage account. scottrade charges a ​$6 commission for online trades. you log into your​ account, check the​ real-time quotes for berkshire hathaway​ (you see a bid price of ​$262 comma 900 and an ask price of ​$263 comma 730​) and submit your order. a. what is the current​ bid/ask spread for berkshire hathaway class a​ shares? b. if scottrade routes your buy order to the​ nyse, where berkshire hathaway is​ listed, what's the potential minimum your total transaction costs will​ be? c.​ if, instead, scottrade routes your buy order to​ nasdaq, where berkshire hathaway is not​ listed, what's the potential maximum your total transaction costs will​ be? d. regardless of how your trade is​ executed, based on the​ bid/ask spread, what is the market value of your​ trade? a. the current​ bid/ask spread for berkshire hathaway class a shares is ​$ nothing. ​(round to the nearest​ dollar.)