题库搜索>问题求解PS-12234
A jar contains 16 marbles, of which 4 are red, 3 are blue, and the rest are yellow. If 2 marbles are to be selected at random from the jar, one at a time without being replaced, what is the probability that the first marble selected will be red and the second marble selected will be blue?
分析A选项
分析B选项
分析C选项
分析D选项
分析E选项
第一个选红的概率是4/16,第二个选蓝的概率是3/(16-1),两个概率之乘积即为题目所问的概率大小=(4/16)*(3/15)=1/20
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第二次取出的分母应该是 15,而不是12
Cancys
不放回的有序概率问题
shneggenhua
有序的排列组合:
A(4,1)*A(3,1)/A(2,16)=4!/3 * 3!/2! / (16!/14!)=1/20
无序的排列组合是C的
默默
两个同时发生时间的概率相乘
科目:
问题求解PS
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2m14s
平均耗时
84.4%
平均正确率
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