作者sunnypace (蜗牛)
看板Statistics
标题[问题] 一题关於机率的问题
时间Mon Nov 9 00:37:32 2009
想请问大家一题机率的问题
Researchers determined that children under 2 years old who sleep with
the lights on have a 36% chance of becoming myopic before they are 16。
Children who sleep in darkness have a 21% probability of becoming myopic。
A survey indicates that 28% of children under 2 sleep with some light on。
Find the probability that a child under 16 ismyopic。
答案是0.2520
想了很久~还是算不出来@@
那部份主要讲树状图
麻烦大家了~
谢谢!!!!!!!!
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1F：推 ksherry:0.36*0.28 + 0.21*0.72 11/09 05:52
2F：→ sunnypace:谢谢楼上帮忙!!^^ 11/09 22:38