GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 19 Jul 2018, 17:43

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

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

Author Message
TAGS:

### Hide Tags

Manager
Joined: 17 Jan 2010
Posts: 139
Concentration: General Management, Strategy
GPA: 3.78
WE: Engineering (Manufacturing)
Ten years ago, scientists predicted that the animal z would  [#permalink]

### Show Tags

13 Feb 2010, 16:38
9
11
00:00

Difficulty:

95% (hard)

Question Stats:

47% (00:53) correct 53% (01:00) wrong based on 356 sessions

### HideShow timer Statistics

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.
Math Expert
Joined: 02 Sep 2009
Posts: 47112

### Show Tags

13 Feb 2010, 17:18
7
6
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.

_________________
##### General Discussion
GMAT Tutor
Joined: 24 Jun 2008
Posts: 1345

### Show Tags

13 Feb 2010, 17:21
2
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.
_________________

GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com

Manager
Joined: 17 Jan 2010
Posts: 139
Concentration: General Management, Strategy
GPA: 3.78
WE: Engineering (Manufacturing)

### Show Tags

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.
CEO
Status: Nothing comes easy: neither do I want.
Joined: 12 Oct 2009
Posts: 2657
Location: Malaysia
Concentration: Technology, Entrepreneurship
Schools: ISB '15 (M)
GMAT 1: 670 Q49 V31
GMAT 2: 710 Q50 V35

### Show Tags

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
_________________

Fight for your dreams :For all those who fear from Verbal- lets give it a fight

Money Saved is the Money Earned

Jo Bole So Nihaal , Sat Shri Akaal

GMAT Club Premium Membership - big benefits and savings

Gmat test review :
http://gmatclub.com/forum/670-to-710-a-long-journey-without-destination-still-happy-141642.html

Manager
Joined: 17 Jan 2010
Posts: 139
Concentration: General Management, Strategy
GPA: 3.78
WE: Engineering (Manufacturing)

### Show Tags

14 Feb 2010, 12:32
1
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
CEO
Status: Nothing comes easy: neither do I want.
Joined: 12 Oct 2009
Posts: 2657
Location: Malaysia
Concentration: Technology, Entrepreneurship
Schools: ISB '15 (M)
GMAT 1: 670 Q49 V31
GMAT 2: 710 Q50 V35

### Show Tags

14 Feb 2010, 12:40
oh..haha....sahi
_________________

Fight for your dreams :For all those who fear from Verbal- lets give it a fight

Money Saved is the Money Earned

Jo Bole So Nihaal , Sat Shri Akaal

GMAT Club Premium Membership - big benefits and savings

Gmat test review :
http://gmatclub.com/forum/670-to-710-a-long-journey-without-destination-still-happy-141642.html

Senior Manager
Joined: 22 Dec 2009
Posts: 322

### Show Tags

14 Feb 2010, 13:40
This question is DS + CR mixed!
_________________

Cheers!
JT...........
If u like my post..... payback in Kudos!!

|For CR refer Powerscore CR Bible|For SC refer Manhattan SC Guide|

~~Better Burn Out... Than Fade Away~~

Manager
Joined: 17 Jan 2010
Posts: 139
Concentration: General Management, Strategy
GPA: 3.78
WE: Engineering (Manufacturing)

### Show Tags

14 Feb 2010, 14:15
jeeteshsingh wrote:
This question is DS + CR mixed!

That is true
Senior Manager
Joined: 19 Nov 2007
Posts: 433

### Show Tags

14 Feb 2010, 19:05
its a good question!
+1
_________________

-Underline your question. It takes only a few seconds!
-Search before you post.

Intern
Joined: 05 Jul 2012
Posts: 4
Re: Ten years ago, scientists predicted that the animal z would  [#permalink]

### Show Tags

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)
Math Expert
Joined: 02 Sep 2009
Posts: 47112
Re: Ten years ago, scientists predicted that the animal z would  [#permalink]

### Show Tags

15 Aug 2012, 00:33
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.
_________________
Director
Joined: 22 Mar 2011
Posts: 604
WE: Science (Education)
Re: Ten years ago, scientists predicted that the animal z would  [#permalink]

### Show Tags

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.

_________________

PhD in Applied Mathematics
Love GMAT Quant questions and running.

Math Expert
Joined: 02 Sep 2009
Posts: 47112
Re: Ten years ago, scientists predicted that the animal z would  [#permalink]

### Show Tags

15 Aug 2012, 02:30
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.
_________________
Director
Joined: 22 Mar 2011
Posts: 604
WE: Science (Education)
Re: Ten years ago, scientists predicted that the animal z would  [#permalink]

### Show Tags

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...
_________________

PhD in Applied Mathematics
Love GMAT Quant questions and running.

Manager
Joined: 22 Aug 2014
Posts: 174
Re: Ten years ago, scientists predicted that the animal z would  [#permalink]

### Show Tags

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?
Manager
Joined: 23 Jun 2009
Posts: 196
Location: Brazil
GMAT 1: 470 Q30 V20
GMAT 2: 620 Q42 V33
Re: Ten years ago, scientists predicted that the animal z would  [#permalink]

### Show Tags

09 Nov 2016, 10:59
here is my two cents!
Attachments

Foto.jpg [ 98.28 KiB | Viewed 1361 times ]

Director
Joined: 26 Oct 2016
Posts: 664
Location: United States
Schools: HBS '19
GMAT 1: 770 Q51 V44
GPA: 4
WE: Education (Education)
Re: Ten years ago, scientists predicted that the animal z would  [#permalink]

### Show Tags

15 Jan 2017, 21:35
The question does not ask for the actual number of years ago that animal z became extinct. Instead it asks for t, the number of years scientists predicted it would take for animal z to become extinct.

(1) INSUFFICIENT: This tells us that animal z became extinct 4 years ago but it does not provide information about t.

(2) INSUFFICIENT: This provides a relationship between the predicted time of extinction time and the actual time of extinction but does not provide any actual values for either.

(1) AND (2) INSUFFICIENT: The easiest way to approach this problem is to imagine a time line from 0 to 10. The scientists made their prediction 10 years ago, or at 0 years.

From statement (1) we know that animal z became extinct 4 years ago, or at 6 years.

From statement (2) we know that if the scientists had extended their prediction by 3 years they would have been incorrect by 2 years. The key to this question is to realize that "incorrect by 2 years" could mean 2 years in either direction: 6 + 2 = 8 years or 6 – 2 = 4 years.

From here, we can write two simple equations:

t + 3 = 8 OR t + 3 = 4
t = 5 t = 1

This gives us two different values for t, which means that (1) and (2) together are not sufficient to come up with one definitive value for t. The correct answer is E.
_________________

Thanks & Regards,
Anaira Mitch

Manager
Joined: 30 Jul 2014
Posts: 147
GPA: 3.72
Re: Ten years ago, scientists predicted that the animal z would  [#permalink]

### Show Tags

20 May 2017, 04:42
I have done the same silly mistake twice in this question . "Actually extinct" v/s "extinct" .
Could anyone help me to improve on such things - it would be a great help.
_________________

A lot needs to be learned from all of you.

Manhattan Prep Instructor
Joined: 04 Dec 2015
Posts: 549
GMAT 1: 790 Q51 V49
GRE 1: Q170 V170
Re: Ten years ago, scientists predicted that the animal z would  [#permalink]

### Show Tags

20 May 2017, 09:42
DAakash7 wrote:
I have done the same silly mistake twice in this question . "Actually extinct" v/s "extinct" .
Could anyone help me to improve on such things - it would be a great help.

Can you elaborate a little bit on what you mean by this? If you could write out your solution (including where you went wrong), I'd be able to help.
_________________

Chelsey Cooley | Manhattan Prep Instructor | Seattle and Online

My upcoming GMAT trial classes | GMAT blog archive

Re: Ten years ago, scientists predicted that the animal z would &nbs [#permalink] 20 May 2017, 09:42
Display posts from previous: Sort by

# Events & Promotions

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.