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# There are 10 items, you will pick three items out of these

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Intern
Joined: 06 Jan 2006
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There are 10 items, you will pick three items out of these [#permalink]

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19 Feb 2006, 14:23
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

There are 10 items, you will pick three items out of these 10, what is the probability that the items you pick contain the most expensive 2 of the 10?

How would you solve this problem? I don't really know where to start.
My tentative solution is 2/10 + 1/10 + 8/10 The first 2/10 is the probability of picking one of the two most expensive item, then 1/10 indicates picking the other one of the two, then 8/10 indicates everything else is fair game.

I think I'm totally going about this the WRONG way. How would you solve it? Probability problems give me migranes! .......
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19 Feb 2006, 15:19
Here is what I think:

Total combinations = 10C3

Possibilities : All combninations where the two most expensive items appear

E1, E2, X (X cab be any of the other 8 items)
= 1*1*8 = 8

Reqd Probability = 8/10C3 = 1/15
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19 Feb 2006, 18:50
Total possibilites = 10C3 = 120
Assuming we have picked out 2 of the most expensive items, then third item can only be any one of the remainig 8. So total possibilites = 8

P = 8/120 = 1/15

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19 Feb 2006, 18:50
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# There are 10 items, you will pick three items out of these

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