鴻池です。

"Eiji KATSURA" <blackhole(I_dont_read_mails)@hamaint.co.jp> wrote in message
news:030626181005.M0131277@psv.hamaint.co.jp...
> <3EF9ADAE.F9B1F1B1@apionet.or.jp>の記事において
> eurms@apionet.or.jpさんは書きました。
>
> > > <3EF86987.53CD6180@apionet.or.jp>の記事において
> > > eurms@apionet.or.jpさんは書きました。
> 100回? 1000回? 10000回?
>
> > 何なら、自分で実験していたら？
>
> それは、無理な相談。
> ランダムに投げたら、50cmの線分が10cm程度の円と交わることなど
> 一生投げ続けても起こりませんよ。

全くの素人で話はよく分かりませんが，ｗｅｂで以下のようなものを見つけました。
それによるとM_SHIRAISHIさん以外にも実際試した人もいるようで，その人の場合，
実験の結果は1/2になったようです。

以下　http://www.cut-the-knot.org/bertrand2.shtml　からの抜粋。

I have found your site and find it very interesting. However, I have a
comment on your page on Bertrand's Paradox.

You give two different solutions:

First Solution.
Assign a uniform probability distribution to the angles of intersection of
the cord on the circumference. Then p=1/3.

Second Solution
Assign a uniform probability distribution to the center of the chord over
the area of the circle. p=1/4.

There actually is a third intuitive solution:

Assign a uniform probability distribution to the linear distance between
centers of chord and circle midpoint.

E.T.Jaynes has given a very sound argument for this third solution in his
paper "The Well-Posed Problem". His own, very careful words about his
viewpoint:

中略

Jaynes has actually proved analytically that solution three is the only
possible solution for which the "rain of straws" carries no information at
all about the target circle it is thrown on. However, he still does not say
that he has "solved" Bertrand's paradox:

While it would perhaps be overstating the case to say that this new
viewpoint is more `correct' in principle than the conventional one, it will
surely be more useful in practice."

(By the way: Dr. Charles Tyler has really thrown straws, until he had 128
hits, and has clearly confirmed the third solution by measurements).

上で書かれているE.T.Jaynesの　"The Well-Posed Problem"は，下記のURLで読める
ようです。

http://bayes.wustl.edu/etj/articles/well.pdf

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