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Director
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When a die that has one of six consecutive integers on each [#permalink]
 04 Oct 2004, 17:56
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When a die that has one of six consecutive integers on each of its sides is rolled twice, what is the probability of getting the number 1 on both rolls?
(1) the probability of NOT getting an eight is 1
(2) the probability of NOT getting a seven is 25/36
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Director
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1. Since prob of not getting a 8 is 1. Then there is no number 8 in the die. We dont know if number 1 is still there. So, Insuff.
2. The prob of not getting 7 is 25/36. Essentially means there is number 7. 25/36 is because in the first roll the prob of not getting 7 is (1-1/6) which is 5/6 and similarly in the second roll toalling to 25/36. Since 7 is there and the numbers are CONSECUTIVE, the numbers have to be (in a worst case scenario) 2-7 or can be 3-8 or anything else that includes 7. - but definitely does not include 1. So, Suff.
B.
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GMAT Club Legend
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great explanation venksune. I totally agree.
_________________
Best Regards,
Paul
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VP
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Good point...I like this problem, very good one.
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Senior Manager
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Forgot to log in..
BTW: The question should state that there can only be 1 digit on each side, not just an Integer.
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Intern
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gr8 detailed explanation
thank u
gr8 :idea:
-anish
[quote="venksune"]1. Since prob of not getting a 8 is 1. Then there is no number 8 in the die. We dont know if number 1 is still there. So, Insuff.
2. The prob of not getting 7 is 25/36. Essentially means there is number 7. 25/36 is because in the first roll the prob of not getting 7 is (1-1/6) which is 5/6 and similarly in the second roll toalling to 25/36. Since 7 is there and the numbers are CONSECUTIVE, the numbers have to be (in a worst case scenario) 2-7 or can be 3-8 or anything else that includes 7. - but definitely does not include 1. So, Suff.
B.[/quote]
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close
