[問題] 統計的機率問題>"<
想請問一下這題統計問題 搞不太清楚在問什麼@@
Mary lives at O in the accompanying diagram and has four friends who
live atA,B,C,D. One day Mary decides to go visiting, so she tosses
a fair coin twice to decide which of the four to visit.
Once at a friend's house, she will either return home or proceed to
one of the two neighbors (such as O,A,C when atB) with each of
the three possibility having probability 1/3.
In this way Mary continues to visit friends until she returns home.
A___________ B
|＼ ／| 正方形(不好意思 畫的很差orz)
| ＼ ╱ |
| ╳ |
| ╱O ╲ |
|／ ＼|
D—————— C
Let X be the number of times that Mary visits a friend,
Y be the number of straight-line segment that Mary
traverses/穿越/(including those leading to and from O)
Which one of the following statement is true?
A) f(x)=(2/3)*(1/3)^x-1 for x=1,2,3
B) f(y)=(3/4)^y-1 * (1/4) for y=2,3,4,5
C) f(x)=(3/4)^x-2 * (1/4) for x=1,2,3
D) f(y)=(2/3)^y-2 * (1/3) for y=2,3,4,5
X是Mary拜訪朋友次數
Y我就搞不太懂是代表什麼@@
可以問一下大家 這題大概是在問什麼嗎???
因為答案裡的假設我也搞不太懂是為什麼@@"
為什麼是這樣假設呢???
謝謝大家的幫忙了!!!!! Orz
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※ 編輯: kighty 來自: 203.73.85.113 (02/12 15:03)