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The cards in a deck are numbered consecutively from 1 to 20. If some

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vanidhar
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The cards in a deck are numbered consecutively from 1 to 20. If some [#permalink] New post   16 Oct 2010, 05:47
1
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A
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D
E

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55% (hard)

Question Stats:

48% (00:55) correct 52% (00:48) wrong based on 48 sessions
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The cards in a deck are numbered consecutively from 1 to 20. If some cards are red and some cards are black, what is the probability of drawing a red card?

(1) The odd-numbered cards are all red.
(2) The even-numbered cards are all black.

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C
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Re: The cards in a deck are numbered consecutively from 1 to 20. If some [#permalink] New post   16 Oct 2010, 14:55
I think the catch here is that "some cards are red and some cards are black". May be some cards are of other colors too. This would prevent us from assuming that each of the given statements are sufficient and requires both together to determine the probability.
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Re: The cards in a deck are numbered consecutively from 1 to 20. If some [#permalink] New post   16 Oct 2010, 15:21
Fremontian I agree with you.

According to (1) there is still the possibility that some of the even-numbered cards could be also red and if I don't consider that I will falsely underestimate the probability of drawing a red card, so insufficient.

Statement (2) ensures me that the rest of the cards are black,
hence I can exactly estimate the probability if I take both statements together.

Therefore C
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Re: The cards in a deck are numbered consecutively from 1 to 20. If some [#permalink] New post   17 Oct 2010, 03:28
Haha, what a trick. It's good to be aware of this kind of questions. If we wanted the answer D, then it should read something like that:

(1) The odd-numbered cards "only" are all red.
(2) The even-numbered cards "only" are all black.
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Re: The cards in a deck are numbered consecutively from 1 to 20. If some [#permalink] New post   24 Jul 2016, 04:59
good question...its not rocket science as such but the missing word all makes it 700 level :)

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Re: The cards in a deck are numbered consecutively from 1 to 20. If some [#permalink]
24 Jul 2016, 04:59
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