顺序对
Sequential Pairs
题目详情
Sam 有一副标准的 52 副牌。他抽出两张牌,它们恰好具有相同的等级。他接下来抽到的两张牌也具有相同等级的概率是多少?
Sam has a standard 52 deck of cards. He pulls two cards and they happen to share the same rank. What is the probability that the next two cards he draws also share the same rank?
解析
如果 Sam 再抽出两张与他刚刚抽出的牌相同的牌,则有 方法可以做到这一点。
如果他抓到两张相同点数但与上一张不同的牌,则有 方法可以实现此目的。队伍中,和他上次拉的不一样。
假设牌组中剩余牌张为 ,且 Sam 将抽出更多 ,则总共存在 可能的抽牌。
所以我们得到:
Original Explanation
If Sam pulls two more cards of the same rank that he just pulled, there are ways to do this.
If he draws two cards of the same rank but different from his last pair, there are ways of accomplishing this. Of the ranks, of them are different from his last pull.
Given that there are remaining cards in the deck and Sam will pull more, there exist a total of possible drawings.
So we get: