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D01-23

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New post 20 Aug 2017, 10:57
Indeed a high quality question that tests our skills of understanding prime numbers , reciprocals and divisibility.

Though I am not qualified enough to pass any comment or remark on any question, but one thing I am sure is that almost all the questions of Bunuel are truly excellent...

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New post 21 Aug 2017, 03:43
sharmapallavi wrote:
I think this is a poor-quality question and I don't agree with the explanation. For GMAT or OTHERWISE, a SET never has any repetitions. You should have mentioned a LIST instead of a SET in this question.


Yes, you are right. Edited as suggested. Thank you.
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Re: D01-23  [#permalink]

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New post 10 Nov 2017, 14:50
I can certainly see the logic in the explanation with this question, but I answered E. My basis for E is that all the terms could be 1/5 in which case the median is 1/5. My understanding of the wording of the question is the median has to be less than 1/5 to give a hard yes, but if you can have 1/5 as well as 1/2 and 7/20 as answers for #2, there is no clear yes or no. Am I overlooking something on this one?
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New post 11 Nov 2017, 01:28
zflodeen wrote:
I can certainly see the logic in the explanation with this question, but I answered E. My basis for E is that all the terms could be 1/5 in which case the median is 1/5. My understanding of the wording of the question is the median has to be less than 1/5 to give a hard yes, but if you can have 1/5 as well as 1/2 and 7/20 as answers for #2, there is no clear yes or no. Am I overlooking something on this one?


In a Yes/No Data Sufficiency questions, statement(s) is sufficient if the answer is “always yes” or “always no” while a statement(s) is insufficient if the answer is "sometimes yes" and "sometimes no".

The question asks: is the median of the list less than 1/5?

From (2) the median could be 1/2, 1/5 or 7/20. None of the possible values is less than 1/5. So, we have a definite NO answer to the question for all three possible values of the median. Sufficient.

Hope it's clear.
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Re: D01-23  [#permalink]

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New post 11 Nov 2017, 10:12
Thank you Bunuel! That helps to clear up my thinking. I had a lapse in my brain and forgot that 1/2 is greater than 1/5. Thanks again!
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New post 10 Apr 2018, 12:19
Hello Bunuel -

As per choice B - "The product of any two term of the list is terminating decimal".
now the list is of 10 numbers and consists of 1/2 and 1/5. So any two term can be 1/2 and 1/2 also right ???. I was confused about this while answering.
Shouldn't the choice be - "The product of any two distinct term of the list is terminating decimal".

Kindly explain so that I can clear my concept.
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New post 10 Apr 2018, 12:38
madhukaramar wrote:
Hello Bunuel -

As per choice B - "The product of any two term of the list is terminating decimal".
now the list is of 10 numbers and consists of 1/2 and 1/5. So any two term can be 1/2 and 1/2 also right ???. I was confused about this while answering.
Shouldn't the choice be - "The product of any two distinct term of the list is terminating decimal".

Kindly explain so that I can clear my concept.


Why were you confused? Yes, the two terms could be 1/2 and 1/2. Why not? 1/2*1/2 = 1/4 = terminating decimal.
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New post 10 Apr 2018, 13:36
My Bad - to get a terminating decimal - the denominator needs to be in the form of 2(power -n) * 5 (power - n) . N can always be 0 as well. Time pressure - I am sorry.
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New post 01 May 2018, 19:38
I think this is a high-quality question and I agree with explanation. The Statement (2) is sufficient but the reason for sufficiency needs to be explained better because 1/8,1/10,1/4 and so on can also be in the set. But median or any of these values will continue to be lesser than 1/5. So the main reason we chose 1/2 & 1/5 is because they have the highest value that gives terminating decimals when multiplied.

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New post 01 May 2018, 20:58
kittyman wrote:
I think this is a high-quality question and I agree with explanation. The Statement (2) is sufficient but the reason for sufficiency needs to be explained better because 1/8,1/10,1/4 and so on can also be in the set. But median or any of these values will continue to be lesser than 1/5. So the main reason we chose 1/2 & 1/5 is because they have the highest value that gives terminating decimals when multiplied.

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That's not correct. 1/8, 1/10 and 1/4 cannot be in the set because we are told that the set consists of 10 terms, each of which is a reciprocal of a prime number. 8, 10 and 4 are not primes.
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New post 02 May 2018, 03:43
Bunuel wrote:
kittyman wrote:
I think this is a high-quality question and I agree with explanation. The Statement (2) is sufficient but the reason for sufficiency needs to be explained better because 1/8,1/10,1/4 and so on can also be in the set. But median or any of these values will continue to be lesser than 1/5. So the main reason we chose 1/2 & 1/5 is because they have the highest value that gives terminating decimals when multiplied.

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That's not correct. 1/8, 1/10 and 1/4 cannot be in the set because we are told that the set consists of 10 terms, each of which is a reciprocal of a prime number. 8, 10 and 4 are not primes.


Understood Thanks :)


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New post 20 Jun 2018, 07:09
I think this is a high-quality question and I agree with explanation.
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New post 04 Jul 2018, 20:09
Why only 1/2 and 1/5 for statement two? It can also be 1/3, 1/7, 1/11 etc., right?
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New post 04 Jul 2018, 20:17
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Manick9 wrote:
Why only 1/2 and 1/5 for statement two? It can also be 1/3, 1/7, 1/11 etc., right?


No. If there are reciprocals of other primes than 2 and 5, then the product of ANY two terms of the list won't be a terminating decimal. For example, if the list is {1/2, 1/2, 1/2, 1/2, 1/2, 1/2, 1/5, 1/5, 1/5, 1/3}, then no pair with 1/3 will produce the product which is a terminating decimal: 1/2*1/3 = 1/6 = 0.1666666.... and 1/5*1/6 = 0.0333333............... (reduced fraction to be terminating its denominator must have only 2's and/or 5 in it).
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New post 04 Jul 2018, 20:32
Thanks Bunuel!
I didn't understand the definition of terminating decimal clearly at first. I got it confused with recurring decimal.
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Re: D01-23 &nbs [#permalink] 04 Jul 2018, 20:32

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