Cornell MFE 面筋一枚

gaowei1988

虽然都这时候了估计用处不大，就算留点史料吧。

1.对于financial crysis的看法，原因和处理方法（完全没料到。。。）
2.抛硬币，期望几次可以有1个正面，期望几次有连续两正面
3.两人在一圆桌上放硬币（不能叠在别人放的硬币上）最后放不下的人输，问你的策略

就这仨题，别的嘛没问。

doriadodo

第三题怎么做呢？

doladd

LZ和LS说说前两题怎么作吧

第三题怎么做呢？

-- by 会员 doriadodo (2011/4/5 0:16:11)

csx5402

Q3: I will move first, and put the coin in the middle of the table. When your opponent puts the coin anywhere on the table, I can always make my coin symmetric to his.

doriadodo

LZ和LS说说前两题怎么作吧

第三题怎么做呢？

-- by 会员 doriadodo (2011/4/5 0:16:11)

-- by 会员 doladd (2011/4/5 0:19:41)

第二题之前有个面经有的，第一题开放啦

doriadodo

Q3: I will move first, and put the coin in the middle of the table. When your opponent puts the coin anywhere on the table, I can always make my coin symmetric to his.

-- by 会员 csx5402 (2011/4/5 1:51:27)

smart！

gaowei1988

Q3: I will move first, and put the coin in the middle of the table. When your opponent puts the coin anywhere on the table, I can always make my coin symmetric to his.

-- by 会员 csx5402 (2011/4/5 1:51:27)

正解

gaowei1988

LZ和LS说说前两题怎么作吧

第三题怎么做呢？

-- by 会员 doriadodo (2011/4/5 0:16:11)

-- by 会员 doladd (2011/4/5 0:19:41)

见LSLSLS

doladd

前两题


[/quote]

见LSLSLS

-- by 会员 gaowei1988 (2011/4/5 2:17:34)

[/quote]

gaowei1988

前两题

见LSLSLS

-- by 会员 gaowei1988 (2011/4/5 2:17:34)

[/quote]

第一题开放啊，自圆其说就好
第二题借前人帖子一用
found online

Let a = expected number of throws to first head.

We must make 1 throw at least and we haveprobability 1/2 of a head
and probability 1/2 of returning to a, so

 a = (1/2)1 + (1/2)(1 + a)

 (1/2)a = 1

      a = 2.

Let E = expected number of throws to 2 consecutiveheads.

Consider that we have just thrown a head and whathappens on the next
throw.  We are dealing with the (a + 1)ththrow, with probability 1/2
this is not a head and we return to E.

So  E = (1/2)(a + 1) + (1/2)(a + 1 + E)    

(1/2)E = a + 1

     E = 2(a + 1)

and now putting in the value a = 2 we get  E= 2(3)  =  6

Expected throws to 2 consecutive heads is 6.

-- by 会员 doladd (2011/4/5 2:18:19)

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