來源:98年北大企管 Q: Toby Talkalot subscribes to a local phone service that changes a fixed fee of $10 per month and allows him to place as many local phone calls as he likes without further charge. Let good 1 be an aggregate of commodities other than local phone use and let good 2 be local phone use. (Measure good 1 on the horizontal axis and good 2 on the vertical axis.) On Monday, Toby didn't use the telephone at all. The slope m of his indifference curve at the consumption bundle he chose on Monday was A)positive B)less than or equal to 0 C)0 D)greater than 0 E)negative 補習班給的答案是A(但另有詳解寫E) A的解釋是由於縱軸的室內電話費率是0 因此Toby面對的預算限制式為垂直線 若他在星期一的最適選擇是角解橫軸商品 表示此時無異曲線一定是正斜率 選E的詳解表示:雖然星期一沒有使用~但費用已繳~無論有沒有使用電話~都視為已購買 我的想法是:若把電話費率放在縱軸 那他星期一沒有使用的確可看做價格下跌至無窮 但為什麼角解橫軸一定表示無異曲線是正斜率呢? 有請高手解答了!謝謝!! 有在研究所問題板問過 有板友說Varian的課本有這一題 而答案給C 想請問看看到底要怎麼解釋呢? 現在有三個版本啦...QQ ※ 編輯: scodowying 來自: 111.249.192.166 (07/27 00:36)