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# Ten years ago, scientists predicted that the animal z would

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Ten years ago, scientists predicted that the animal z would [#permalink]

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13 Feb 2010, 16:38
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Ten years ago, scientists predicted that the animal z would become extinct in t years. What is t?

(1) Animal z became extinct 4 years ago.

(2) If the scientists had extended their extinction prediction for animal z by 3 years, their prediction would have been incorrect by 2 years.
[Reveal] Spoiler: OA
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13 Feb 2010, 17:18
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Ten years ago, scientists predicted that the animal z would become extinct in t years. What is t?

(1) Animal z became extinct 4 years ago. The only thing we can get from this statement is when animal z actually extincted: 4 years ago or 6 years after the prediction. Not sufficient.

(2) If the scientists had extended their extinction prediction for animal z by 3 years, their prediction would have been incorrect by 2 years. Also not sufficient: t+3=actual extinction +/- 2.

(1)+(2) Animals extincted 6 years after the prediction: t+3=6-2 --> t=1 OR t+3=6+2 --> t=5. Two answers, not sufficient.

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13 Feb 2010, 17:21
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alexBLR wrote:
Ten years ago, scientists predicted that the animal z would become extinct in t years. What is t?

(1) Animal z became extinct 4 years ago.

(2) If the scientists had extended their extinction prediction for animal z by 3 years, their prediction would have been incorrect by 2 years.

From S1 we learn that the animal became extinct 6 years after the scientists made their prediction. Of course, we have no info about t, so this is not sufficient. Similarly S2 is not sufficient, since we have no info about when the animal actually became extinct.

Combining the two Statements, we know that if we add three to t, the value we get will be two away from the correct value, which is, from Statement 1, six. We do not, however, know if it will be two above or two below the correct value, so we will get two different possible values for t. That is, the scientists may have predicted the animal would become extinct in 1 year; adding three, we are off by two from the correct value of 6. Or, they may have predicted the animal would become extinct in 5 years; again, adding three, we are off by two from the correct value of 6. The answer is E.

I'm curious where the question is from; it's a bit different from other questions I've seen.
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13 Feb 2010, 21:54
IanStewart wrote:
alexBLR wrote:
Ten years ago, scientists predicted that the animal z would become extinct in t years. What is t?

(1) Animal z became extinct 4 years ago.

(2) If the scientists had extended their extinction prediction for animal z by 3 years, their prediction would have been incorrect by 2 years.

From S1 we learn that the animal became extinct 6 years after the scientists made their prediction. Of course, we have no info about t, so this is not sufficient. Similarly S2 is not sufficient, since we have no info about when the animal actually became extinct.

Combining the two Statements, we know that if we add three to t, the value we get will be two away from the correct value, which is, from Statement 1, six. We do not, however, know if it will be two above or two below the correct value, so we will get two different possible values for t. That is, the scientists may have predicted the animal would become extinct in 1 year; adding three, we are off by two from the correct value of 6. Or, they may have predicted the animal would become extinct in 5 years; again, adding three, we are off by two from the correct value of 6. The answer is E.

I'm curious where the question is from; it's a bit different from other questions I've seen.

It is from the MGMAT Question Bank.
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14 Feb 2010, 09:48
Bunuel wrote:
(1) The only thing we can get from this statement is when animal z actually extincted: 4 years ago or 6 years after the prediction. Not sufficient.

(2) Also not sufficient: t+3=actual extinction +/- 2.

(1)+(2) Animals extincted 6 years after the prediction: t+3=6-2 --> t=1 OR t+3=6+2 --> t=5. Two answers, not sufficient.

From S1 we get it got extincted 6 years after the prediction. then t =6? they are just asking after how many years of prediction it will be extincted.
Pls correct me where m wrong
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14 Feb 2010, 12:32
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gurpreetsingh wrote:
Bunuel wrote:
(1) The only thing we can get from this statement is when animal z actually extincted: 4 years ago or 6 years after the prediction. Not sufficient.

(2) Also not sufficient: t+3=actual extinction +/- 2.

(1)+(2) Animals extincted 6 years after the prediction: t+3=6-2 --> t=1 OR t+3=6+2 --> t=5. Two answers, not sufficient.

From S1 we get it got extincted 6 years after the prediction. then t =6? they are just asking after how many years of prediction it will be extincted.
Pls correct me where m wrong

I fall into the same trap and assumed that sientists' prediction is acurate. However, in this case the sientists' prediction for time of extinction is not necessarily equal to the time of actual animal extinction
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14 Feb 2010, 12:40
oh..haha....sahi
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14 Feb 2010, 13:40
This question is DS + CR mixed!
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14 Feb 2010, 14:15
jeeteshsingh wrote:
This question is DS + CR mixed!

That is true
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14 Feb 2010, 19:05
its a good question!
+1
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Re: Ten years ago, scientists predicted that the animal z would [#permalink]

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14 Aug 2012, 08:55
Bunuel, this problem, in my view, is ambiguous in its statement. Is t representing only the scientists' prediction, or the actual time of extinction. And in a math problem , shouldn't we be assuming these to be the same.(and not employ our CR skills)
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Re: Ten years ago, scientists predicted that the animal z would [#permalink]

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15 Aug 2012, 00:33
Expert's post
Bunuel, this problem, in my view, is ambiguous in its statement. Is t representing only the scientists' prediction, or the actual time of extinction. And in a math problem , shouldn't we be assuming these to be the same.(and not employ our CR skills)

Well, common sense says that predictions are not 100% precise. But even if you are confused by the first statement, the second one should help to realize that the predicted extinction date and the actual extinction date are not the same.
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Re: Ten years ago, scientists predicted that the animal z would [#permalink]

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15 Aug 2012, 02:23
alexBLR wrote:
Ten years ago, scientists predicted that the animal z would become extinct in t years. What is t?

(1) Animal z became extinct 4 years ago.

(2) If the scientists had extended their extinction prediction for animal z by 3 years, their prediction would have been incorrect by 2 years.

Just my two cents:
I assume that the scientists's prediction is either correct or not, according to the supplied information.

(1) Animal z became extinct 4 years ago or 6 years after the scientists's prediction. Nothing stated about the accuracy of the prediction.
Not sufficient.

(2) In contrast to (1), here we have explicitly stated that t + 3 would be incorrect by 2 years. It means that animal z became extinct in t + 1 years and $$t + 1 \leq10$$ or $$t\leq9$$ because we have already witnessed the extinction.
Not sufficient.

(1) and (2) together:
Scientists predicted t years, but in fact the extinction occurred after t+1 years. We know for sure that this happened 4 years ago or 6 years after the scientists's prediction. This means t + 1= 6 or t = 5.
Sufficient.

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Re: Ten years ago, scientists predicted that the animal z would [#permalink]

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15 Aug 2012, 02:30
Expert's post
EvaJager wrote:
alexBLR wrote:
Ten years ago, scientists predicted that the animal z would become extinct in t years. What is t?

(1) Animal z became extinct 4 years ago.

(2) If the scientists had extended their extinction prediction for animal z by 3 years, their prediction would have been incorrect by 2 years.

Just my two cents:
I assume that the scientists's prediction is either correct or not, according to the supplied information.

(1) Animal z became extinct 4 years ago or 6 years after the scientists's prediction. Nothing stated about the accuracy of the prediction.
Not sufficient.

(2) In contrast to (1), here we have explicitly stated that t + 3 would be incorrect by 2 years. It means that animal z became extinct in t + 1 years and $$t + 1 \leq10$$ or $$t\leq9$$ because we have already witnessed the extinction.
Not sufficient.

(1) and (2) together:
Scientists predicted t years, but in fact the extinction occurred after t+1 years. We know for sure that this happened 4 years ago or 6 years after the scientists's prediction. This means t + 1= 6 or t = 5.
Sufficient.

Both t=1 and t=5 satisfy the statements. So, the answer is E.
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Re: Ten years ago, scientists predicted that the animal z would [#permalink]

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15 Aug 2012, 02:50
Bunuel wrote:
EvaJager wrote:
alexBLR wrote:
Ten years ago, scientists predicted that the animal z would become extinct in t years. What is t?

(1) Animal z became extinct 4 years ago.

(2) If the scientists had extended their extinction prediction for animal z by 3 years, their prediction would have been incorrect by 2 years.

Just my two cents:
I assume that the scientists's prediction is either correct or not, according to the supplied information.

(1) Animal z became extinct 4 years ago or 6 years after the scientists's prediction. Nothing stated about the accuracy of the prediction.
Not sufficient.

(2) In contrast to (1), here we have explicitly stated that t + 3 would be incorrect by 2 years. It means that animal z became extinct in t + 1 years and $$t + 1 \leq10$$ or $$t\leq9$$ because we have already witnessed the extinction.
Not sufficient.

(1) and (2) together:
Scientists predicted t years, but in fact the extinction occurred after t+1 years. We know for sure that this happened 4 years ago or 6 years after the scientists's prediction. This means t + 1= 6 or t = 5.
Sufficient.

Both t=1 and t=5 satisfy the statements. So, the answer is E.

Oops! I missed the -2 possibility...
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Re: Ten years ago, scientists predicted that the animal z would [#permalink]

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12 Aug 2013, 03:39
Expert's post
Bumping for review and further discussion.
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Re: Ten years ago, scientists predicted that the animal z would [#permalink]

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09 Dec 2014, 00:50
Hello from the GMAT Club BumpBot!

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Ten years ago, scientists predicted that the animal z would [#permalink]

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09 Dec 2014, 01:05
Bunuel wrote:
Ten years ago, scientists predicted that the animal z would become extinct in t years. What is t?

(1) Animal z became extinct 4 years ago. The only thing we can get from this statement is when animal z actually extincted: 4 years ago or 6 years after the prediction. Not sufficient.

(2) If the scientists had extended their extinction prediction for animal z by 3 years, their prediction would have been incorrect by 2 years. Also not sufficient: t+3=actual extinction +/- 2.

(1)+(2) Animals extincted 6 years after the prediction: t+3=6-2 --> t=1 OR t+3=6+2 --> t=5. Two answers, not sufficient.

Hello Bunuel, thanks for your massive help

I have a little problem with your conclusion from second statement. I believe that there is no chance to have this situation: "t+3=actual extinction -2"
I believe that the prediction is right when the actual extinction occurs before predicted time ("actual extinction<t" then prediction is right). For instance if scientists have predicted the extinction in 4 yrs and it occurs in 5 yrs, adding 3 yrs to their predicted time, means that they have predicted that extinction occurs in 7 yrs which include the real extinction time. So, actual extinction time must be 9 yrs. So, I believe answer is C
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Re: Ten years ago, scientists predicted that the animal z would [#permalink]

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09 Dec 2014, 08:43
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heartbanger97 wrote:
Bunuel wrote:
Ten years ago, scientists predicted that the animal z would become extinct in t years. What is t?

(1) Animal z became extinct 4 years ago. The only thing we can get from this statement is when animal z actually extincted: 4 years ago or 6 years after the prediction. Not sufficient.

(2) If the scientists had extended their extinction prediction for animal z by 3 years, their prediction would have been incorrect by 2 years. Also not sufficient: t+3=actual extinction +/- 2.

(1)+(2) Animals extincted 6 years after the prediction: t+3=6-2 --> t=1 OR t+3=6+2 --> t=5. Two answers, not sufficient.

Hello Bunuel, thanks for your massive help

I have a little problem with your conclusion from second statement. I believe that there is no chance to have this situation: "t+3=actual extinction -2"
I believe that the prediction is right when the actual extinction occurs before predicted time ("actual extinction<t" then prediction is right). For instance if scientists have predicted the extinction in 4 yrs and it occurs in 5 yrs, adding 3 yrs to their predicted time, means that they have predicted that extinction occurs in 7 yrs which include the real extinction time. So, actual extinction time must be 9 yrs. So, I believe answer is C

Note that the official answer and all the poster above disagree with you.
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Re: Ten years ago, scientists predicted that the animal z would [#permalink]

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20 Apr 2015, 03:40
Bunuel wrote:
Ten years ago, scientists predicted that the animal z would become extinct in t years. What is t?

(1) Animal z became extinct 4 years ago. The only thing we can get from this statement is when animal z actually extincted: 4 years ago or 6 years after the prediction. Not sufficient.

(2) If the scientists had extended their extinction prediction for animal z by 3 years, their prediction would have been incorrect by 2 years. Also not sufficient: t+3=actual extinction +/- 2.

(1)+(2) Animals extincted 6 years after the prediction: t+3=6-2 --> t=1 OR t+3=6+2 --> t=5. Two answers, not sufficient.

Hi Bunuel,
Initially I choose A.Then after analysis,I found that in question scientist predicted that the animal z "would" become extinct in t years.Would is assumption or uncertainty whereas in answer it is given that animal became extinct 4 years ago(certainty).
Is this the right logic to rule out A?
Re: Ten years ago, scientists predicted that the animal z would   [#permalink] 20 Apr 2015, 03:40

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