Q14:
Six cards numbered from 1 to 6 are placed in an empty bowl. First one card is drawn and then put back into the bowl; then a second card is drawn. If the cards are drawn at random and if the sum of the numbers on the cards is 8, what is the probability that one of the two cards drawn is numbered 5 ?
我做出来是1/3，答案是2/5，请帮帮忙！我觉得加起来等于八，只有2和6，3和5，4和4三种组合，所以是1/3！作者: teyvhf 时间: 2004-8-4 06:23
The number of ways that the sum of the numbers on the 2 cards is 8 is 5，i.e., 2,6 6,2 3,55,3 4,4. So th probability that one of the 2 cards drawn is numbered 5 is obviously 2/5.
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