愚昧的問一題 exam p 的問題??? - 金融分析師

可能是英文文法吧
最近做到 exam p 的sample 的第43題

A company takes out an insurance policy to cover accidents that occur at its
manufacturing plant.

The probability that one or more accidents will occur during any given month is 3/5.

The number of accidents that occur in any given month
is independent of the number of accidents that occur in all other months.

Calculate the probability that there will be at least four months in which no accidents
occur before the fourth month in which at least one accident occurs.

就是關於最後一句的翻譯
是在說"在第四個月至少有一次意外發生之前，最少有四個月沒有意外發生"嗎？
好像怪怪的說

看解答也看不出所以然
所以想請問板上有考過P的前輩們能夠幫忙解惑一下
如果能提供另外的作法就更感謝了
謝謝！


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我是新手~

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