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Is st = t ?

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Joined: 19 Jul 2013
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Is st = t ? [#permalink]

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07 Jun 2014, 12:04
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Is st = t ?

(1) s = st

(2) t = ts
[Reveal] Spoiler: OA

Kudos [?]: 8 [1], given: 15

Math Expert
Joined: 02 Sep 2009
Posts: 43323

Kudos [?]: 139428 [0], given: 12790

Re: Is st = t ? [#permalink]

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07 Jun 2014, 12:13
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Is st = t ?

Is $$st = t$$? --> is $$s=1$$ or $$t=0$$ (or both)?

(1) s = st --> $$s=0$$ or $$t=1$$ (or both). Not sufficient.

(2) t = ts. Directly answers the question. Sufficient.

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Location: United States (NC)
Concentration: Operations, Technology
WE: Information Technology (Consulting)
Re: Is st = t ? [#permalink]

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08 Jun 2014, 21:48
Bunuel wrote:
Is st = t ?

Is $$st = t$$? --> is $$s=1$$ or $$t=0$$ (or both)?

(1) s = st --> $$s=0$$ or $$t=1$$ (or both). Not sufficient.

(2) t = ts. Directly answers the question. Sufficient.

Hi Bunuel,

from st (1) : we know that 's' not equals 1 or 't' not equals 0 or both , so is this st not sufficient alone.

Pls clarify
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Re: Is st = t ? [#permalink]

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09 Jun 2014, 01:02
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thoufique wrote:
Bunuel wrote:
Is st = t ?

Is $$st = t$$? --> is $$s=1$$ or $$t=0$$ (or both)?

(1) s = st --> $$s=0$$ or $$t=1$$ (or both). Not sufficient.

(2) t = ts. Directly answers the question. Sufficient.

Hi Bunuel,

from st (1) : we know that 's' not equals 1 or 't' not equals 0 or both , so is this st not sufficient alone.

Pls clarify

Consider this:
If $$s=0$$ and $$t\neq{0}$$ ($$s = st$$), then $$st\neq{t}$$. Or if $$t=1$$ and $$s\neq{1}$$ ($$s = st$$), then $$st\neq{t}$$. So, for these cases the answer to the question is NO.

If $$s=t=0$$ ($$s = st$$), then $$st={t}$$. Or if $$s=t=1$$ ($$s = st$$), then $$st={t}$$. So, for these cases the answer to the question is YES.

Does this make sense?
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Re: Is st = t ? [#permalink]

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09 Jun 2014, 09:12
Quote:
Consider this:
If $$s=0$$ and $$t\neq{0}$$ ($$s = st$$), then $$st\neq{t}$$. Or if $$t=1$$ and $$s\neq{1}$$ ($$s = st$$), then $$st\neq{t}$$. So, for these cases the answer to the question is NO.

If $$s=t=0$$ ($$s = st$$), then $$st={t}$$. Or if $$s=t=1$$ ($$s = st$$), then $$st={t}$$. So, for these cases the answer to the question is YES.

Does this make sense?

Yes Bunuel, when we consider values it makes sense.
But I am unable to get to this directly with out plugging values.
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Re: Is st = t ? [#permalink]

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10 Jun 2017, 07:13
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Bunuel wrote:
Is st = t ?

Is $$st = t$$? --> is $$s=1$$ or $$t=0$$ (or both)?

(1) s = st --> $$s=0$$ or $$t=1$$ (or both). Not sufficient.

(2) t = ts. Directly answers the question. Sufficient.

For (1)

could be also assume following cases ?

case 1: s=t=0 then s=st

case 2: s=5,t=1 then s≠st

thanks =)
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Re: Is st = t ? [#permalink]

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08 Dec 2017, 10:02
Bunuel wrote:
Is st = t ?

Is $$st = t$$? --> is $$s=1$$ or $$t=0$$ (or both)?

(1) s = st --> $$s=0$$ or $$t=1$$ (or both). Not sufficient.

(2) t = ts. Directly answers the question. Sufficient.

@bunnel If we have a statement that restates the question , then it becomes insufficient as we don't have any additional information to answer the question. But here the equality nullifies it and directly answers the question. Hence it is sufficient. IS this reasoning correct ?
i

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Re: Is st = t ? [#permalink]

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08 Dec 2017, 10:09
Raksat wrote:
Bunuel wrote:
Is st = t ?

Is $$st = t$$? --> is $$s=1$$ or $$t=0$$ (or both)?

(1) s = st --> $$s=0$$ or $$t=1$$ (or both). Not sufficient.

(2) t = ts. Directly answers the question. Sufficient.

@bunnel If we have a statement that restates the question , then it becomes insufficient as we don't have any additional information to answer the question. But here the equality nullifies it and directly answers the question. Hence it is sufficient. IS this reasoning correct ?
i

Not sure I can follow you.

Say the question asks: is x = 1? And (1) says that x = 1. In this case (1) is sufficient as it directly answers the question: YES x does equal to 1. This is EXACTLY the case we have with the above question.
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Re: Is st = t ? [#permalink]

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08 Dec 2017, 10:54
Bunuel wrote:
Raksat wrote:
Bunuel wrote:
Is st = t ?

Is $$st = t$$? --> is $$s=1$$ or $$t=0$$ (or both)?

(1) s = st --> $$s=0$$ or $$t=1$$ (or both). Not sufficient.

(2) t = ts. Directly answers the question. Sufficient.

@bunnel If we have a statement that restates the question , then it becomes insufficient as we don't have any additional information to answer the question. But here the equality nullifies it and directly answers the question. Hence it is sufficient. IS this reasoning correct ?
i

Not sure I can follow you.

Say the question asks: is x = 1? And (1) says that x = 1. In this case (1) is sufficient as it directly answers the question: YES x does equal to 1. This is EXACTLY the case we have with the above question.

Its about the difference between a tautological statement and this question. Reference question : https://gmatclub.com/forum/in-the-diagr ... 94414.html
In the explanation you explained " This statement repeats information in the prompt, and contains no new information, so it doesn’t help us at all to figure out anything else. This statement, alone and by itself, is not sufficient."
Here B is also reintroducing the information in question.
what's the difference ?

Kudos [?]: 6 [0], given: 437

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Re: Is st = t ? [#permalink]

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08 Dec 2017, 11:00
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Expert's post
Raksat wrote:
Bunuel wrote:
Raksat wrote:
@bunnel If we have a statement that restates the question , then it becomes insufficient as we don't have any additional information to answer the question. But here the equality nullifies it and directly answers the question. Hence it is sufficient. IS this reasoning correct ?
i

Not sure I can follow you.

Say the question asks: is x = 1? And (1) says that x = 1. In this case (1) is sufficient as it directly answers the question: YES x does equal to 1. This is EXACTLY the case we have with the above question.

Its about the difference between a tautological statement and this question. Reference question : https://gmatclub.com/forum/in-the-diagr ... 94414.html
In the explanation you explained " This statement repeats information in the prompt, and contains no new information, so it doesn’t help us at all to figure out anything else. This statement, alone and by itself, is not sufficient."
Here B is also reintroducing the information in question.
what's the difference ?

In the question you quote one of the statements says something that is generally true, so it adds not new info. It says something like x = x, that is generally true.

Here the question asks is $$st = t$$? (2) says t = ts. So, it gives an YES answer to the question.
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Re: Is st = t ?   [#permalink] 08 Dec 2017, 11:00
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