[理工] 機率
Suppose that 20 sticks are broken,each into one long and one short part.
By pairing them randomly, the 40 parts are then used to make 20 new
sticks.
(a) What is the porb. that long parts are all paired with short ones?
(b) What ia the prob. that the new sticks are exactly the same as the old
ones?
要怎麼解??
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