[求助]GWD-2 Q11

asasasas1

Q11:哪位大侠帮忙解释一下？（贴图和原题不太一样，建议看看原来的图利）谢谢

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1 2 3 4

The figure shown represents a board with 4 rows of pegs, and at the bottom of the board are 4 cells numbered 1 to 4. Whenever the ball shown passes through the opening between two adjacent pegs in the same row, it will hit the peg directly beneath the opening. The ball then has the probability 1/2 of passing through the opening immediately to the left of that peg and probability 1/2 of passing through the opening immediately to the right. What is the probability that when the ball passes through the first two pegs at the top it will end in Cell 2?

A. 1/16

B. 1/8

C. 1/4

D. 3/8

E. 1/2

himba

这道题目考的是细心，你就一个一个数。我有点印象，答案好像是D。

没有技巧，就是数。