一个人花8块钱买了一只鸡，9块钱卖掉了，

然后他觉得不划算，花10块钱又买回来了，

11块卖给另外一个人。问他赚了多少？





提示：这是国外某著名商业公司的一道面试题，考查的不是你的数学计算，而是看你会不
会在经济活动中将“如何获得最大利润”放在首位来思考，也测试你在纷杂的交易过程中
能不能明确自己的位置。据说这道题测试过上千人，正确率不足5%，认真考虑，仔细作答
哦！

總共賺37元

一元

2元

3

Why $37?

How did you arrive $37?

Please advise.

Thanks.

I can tell Myron is one of smartest guys herein. Thanks for excellence question.

This is an excellence question to test out the way how people think. The final answer is not important. There is no right or wrong answer. The process/methodology used to come to such result is more important than the result itself.

For pure simple mathematic calculation, it is ($9-$8) + ($11-$10) = $2. Every one can get this answer correctly.

However, for non mathematic considerations, there is no standard answer to the question.
The reason is that there are no enough data points in the question to correctly answer the question.

For example:

1. Does he have enough holding/carry power?
2. How long is the time between he bought at $8 and sold at $9?
3. How long is the time between he sold for $9 and buy back at $10?
4. How long is the time between he bought at $10 and sold at $11?
5. What is the carry cost in each time period? --- Margin cost, cost of money, etc.
6. What is price data during each time period? --- Historic price action.
7. What is the risk consideration which can significantly impact the price)? Such as N1H1, , N1H2, N2H2…. NnHn, 911, etc……
8. Does he need money between the time he sole and re-purchase?
9. What is the daily volume?
10. What is the volume we are talking about?
11. What are the demand and supply?
12. What is the cost of conduct those transactions (1 round trips vs. two round trips, etc)?
13. etc.

In this particular question, we need to have more data points in order to understand the whole picture to make decision. Any one can ask any question with limited information. If input is garbage the output is most like garbage as well.

Collecting enough data points is one important thing to do first before any investment. This question demonstrates that do not trust any one or any investment opportunity before you have enough trustable data points to validate such opportunity.

So, my final answer to the question is: I STILL DO NOT KNOW which is also called “ISDN” which also means “Integrated Services Digital Network” which is a proprietary trading system development network to develop a proprietary trading system.

Great

Ｗell, I'm definitely not a smart guy here. Especially there are so many gurus watching this forums. We all know they are really good.

For me, this question is quite similar to: http://www.moneyq.org/forum/index.php?showtopic=22189
The answer is quite straight for me. But we can always hear different voices since this diverse world.

I'm also interested in the 總共賺37元 answer. How do you approach that?