题目

Andrea and Beth are dining at a fine restaurant. There is a bottle of 2009 Grgich Hills Chardonnay on the menu and the price is $100. To keep things simple, albeit unrealistic, assume the restaurant only sells whole bottles and this is the only wine they carry.

Andrea would be willing to pay $110 to drink the whole bottle.

Andrea would be willing to pay $90 to drink half the bottle.

Beth would be willing to pay $80 to drink the whole bottle.

Beth would be willing to pay $50 to drink half the bottle.

They would like to share a bottle if it makes sense to do so (and if they can agree on how to divide the costs). To see if it makes sense, what is the pie, in dollars?

Note: In the past, nearly 90% of learners got this question wrong on the first try. To help you get into the 10%, please take a moment to think through the potential benefit from reaching an agreement and what each party would do absent a deal.

答案：

If there is no deal A: spend $100 to drink a bottle, meaning he saves $10, or he gets $10 B: nothing

So A and B save/get 10 in total

If there is a deal: A: spend 90 to drink half B: spend 50 to drink a half

A and B get/save $(90+50 - 100) = $40

If there is a deal, the extra benefit is 40 - 10 = 30 compare to not having a deal.

So the pie is 30.

A拿30里的15，然后加上自己之前省的10，总共省25， 90-25 = 65