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Re: Probability [#permalink]
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There are \(C_1^{600}\) or 600 ways of choosing a certain safe deposit box.
Similarly, there are \(C_1^{700}\) or 700 ways of choosing a key to open the box.

To open the box, the thief must choose the corresponding 300 boxes for which he has the keys.

Therefore, the probability that the thief will be able to open the box is \(\frac{1*300}{600*700} = \frac{1}{1400}\)

PS: please post the question under the right subforum: ps is it is a ps, numeric entry if it is a NE.

Moreover, this should be a problem solving
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Re: A certain bank vault contains 600 safe deposit boxes. [#permalink]
Hello from the GRE Prep Club BumpBot!

Thanks to another GRE Prep Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Re: A certain bank vault contains 600 safe deposit boxes. [#permalink]
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