{"image_url":null,"provider_url":"https://hatena.blog","description":"\u4ee3\u6570\u7684\u306b\u671f\u5f85\u5024\u3092\u6c42\u3081\u3088\u3046\u3002 n\u4eba\u3067\u30b8\u30e3\u30f3\u30b1\u30f3\u3057\u3066\u6c7a\u7740\u304c\u3064\u304f\u307e\u3067\u306e\u56de\u6570\u306e\u671f\u5f85\u5024\u3092E(n)\u3068\u3059\u308b\u3002 2\u4eba\u306e\u5834\u5408\u3001 \u3069\u3061\u3089\u304b\u304c\u52dd\u3064\u78ba\u7387\u304c2/3\u3001\u3042\u3044\u3053\u306e\u78ba\u7387\u304c1/3\u3060\u304b\u3089\u3001 1\u56de\u3067\u6c7a\u7740\u304c\u3064\u304f\u78ba\u7387\u306f2/3\u3001 2\u56de\u3067\u6c7a\u7740\u304c\u3064\u304f\u78ba\u7387\u306f1/3 * 2/3 = 2/9\u3001 3\u56de\u3067\u6c7a\u7740\u304c\u3064\u304f\u78ba\u7387\u306f1/3 * 1/3 * 2/3 = 2/27\u3001 \u3068\u306a\u308b\u3002 \u671f\u5f85\u5024\u306f\u3001 E(2) = 1 * 2/3 + 2 * 2/9 + 3 * 2/27 + ... = 3/2 \u3068\u306a\u308b\u3002 3\u4eba\u306e\u5834\u5408\u3001 1\u4eba\u304c\u6b8b\u308b\u78ba\u7387\u306f1/3\u30012\u4eba\u304c\u6b8b\u308b\u78ba\u7387\u306f1/3\u3001\u3042\u3044\u3053\u306e\u78ba\u7387\u306f1/3\u3002 1\u56de\u3067\u6c7a\u7740\u304c\u3064\u304f\u78ba\u7387\u306f1/3\u3001 2\u56de\u3067\u6c7a\u7740\u304c\u3064\u304f\u78ba\u7387\u306f\u3001 3\u2026","author_name":"inamori","provider_name":"Hatena Blog","type":"rich","height":"190","blog_title":"inamori\u2019s diary","version":"1.0","html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Finamori.hateblo.jp%2Fentry%2F20070711%2Fp1\" title=\"\u30b8\u30e3\u30f3\u30b1\u30f3\u3067\u6c7a\u7740\u304c\u3064\u304f\u307e\u3067\u306e\u56de\u6570\uff083\uff09 - inamori\u2019s diary\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","categories":["\u6570\u5b66"],"url":"https://inamori.hateblo.jp/entry/20070711/p1","width":"100%","title":"\u30b8\u30e3\u30f3\u30b1\u30f3\u3067\u6c7a\u7740\u304c\u3064\u304f\u307e\u3067\u306e\u56de\u6570\uff083\uff09","blog_url":"https://inamori.hateblo.jp/","published":"2007-07-11 00:00:00","author_url":"https://blog.hatena.ne.jp/inamori/"}