題目網址: http://www.puzzleup.com/2016/
http://www.puzzleup.com/2016/puzzle/?11
答題時限: 10月６日７ＰＭ－比賽結束（約12月14日）
加分時限: 10月６日７ＰＭ－10月12日６：５９ＰＭ
答對可得基本分１００分。答案可上傳５次，每改１次答案從基本分扣２０分。　
比賽期間內可隨時上傳答案，加分時限內答對第ｎ天加（６－ｎ）分　 　　 　　
另依題目的難易有額外加分（如有８０％的人這題答錯，答對者加８０分）　　
◆PROBABILITY OF RAIN
If the probability of rain on exactly 5 days in a week is the same as the
probability of rain on exactly 6 days in a week what is the probability of
rain on a day?
Notes:
- The probability of rain on each day is the same, and it is greater than
zero, and smaller than one.
- The days with rain (5 days and 6 days) can be in any order.
Enter your answer as a simplified fraction. Example:12/23
若一週內恰好五天下雨的機率和一週內恰好六天內下雨的機率相等，
則一天下雨的機率是多少？
註:
* 此「一天下雨的機率」是固定的，且大於零並小於一。
* 實際下雨日子 (即這五天或六天) 可以是任意組合。
以最簡分數回答，如 12/23。
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又是高中機率題...