国际顶尖MBA申请交流平台--TOPWAY MBA

标题: 一道XDF的概率题 [打印本页]

作者: marinezhenger 时间: 2007-12-15 07:20 标题: 一道XDF的概率题

Forty percent of rats included in an experiment were male rats. If some of the rats died during the experiment, 30 percent of the rats that died were male rats, what was the ratio of death rate among the male rats to the death rate among female rats?

a. 9/14 b. 3/4 c. 9/11 d. 6/7 e. 7/8

答案是A,可我怎么算都觉得缺条件啊。望各位大牛指教！

作者: bloomingdales 时间: 2007-12-15 19:30

把题目看清楚就可以啦 ,求thedeath rate among the male rats /the death rate among female rats

设总共有X参加实验，死了Y

有0.6X FEMAL RATS，0.4X MALE RATS 死0.3Y MALE RATS 0.7Y FEMALE RATS

有0.3Y /0.4X /（0.7Y /0.6X）=9/14

作者: marinezhenger 时间: 2007-12-16 06:23

太感谢了！！！我把相除的关系想成相乘的关系了。恍然大悟！

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