It is currently 20 Oct 2017, 22:44

Close

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
Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Two decades after the Emerald River Dam was built, none of

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

2 KUDOS received
VP
VP
avatar
Joined: 16 Jul 2009
Posts: 1489

Kudos [?]: 1450 [2], given: 2

Schools: CBS
WE 1: 4 years (Consulting)
Two decades after the Emerald River Dam was built, none of [#permalink]

Show Tags

New post 03 May 2010, 14:15
2
This post received
KUDOS
8
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

85% (01:30) correct 15% (02:03) wrong based on 1071 sessions

HideShow timer Statistics

Official Guide for GMAT Verbal Review, 2nd Edition

Practice Question
Question No.: 35
Page: 129
Difficulty:


Two decades after the Emerald River Dam was built, none of the eight fish species native to the Emerald River was still reproducing adequately in the river below the dam. Since the dam reduced the annual range of water temperature in the river below the dam from 50 degrees to 6 degrees, scientists have hypothesized that sharply rising water temperatures must be involved in signaling the native species to begin the reproductive cycle.

Which of the following statements, if true, would most strengthen the scientists’ hypothesis?
(A) The native fish species were still able to reproduce only in side streams of the river below the dam where the annual temperature range remains approximately 50 degrees.
(B) Before the dam was built, the Emerald River annually overflowed its banks, creating backwaters that were critical breeding areas for the native species of fish.
(C) The lowest recorded temperature of the Emerald River before the dam was built was 34 degrees, whereas the lowest recorded temperature of the river after the dam was built has been 43 degrees.
(D) Nonnative species of fish, introduced into the Emerald River after the dam was built, have begun competing with the declining native fish species for food and space.
(E) Five of the fish species native to the Emerald River are not native to any other river in North America.
[Reveal] Spoiler: OA

_________________

The sky is the limit
800 is the limit


GMAT Club Premium Membership - big benefits and savings

Kudos [?]: 1450 [2], given: 2

1 KUDOS received
Current Student
User avatar
Status: What's your raashee?
Joined: 12 Jun 2009
Posts: 1837

Kudos [?]: 273 [1], given: 52

Location: United States (NC)
Concentration: Strategy, Finance
Schools: UNC (Kenan-Flagler) - Class of 2013
GMAT 1: 720 Q49 V39
WE: Programming (Computer Software)
Reviews Badge
Re: Emerald River Dam [#permalink]

Show Tags

New post 03 May 2010, 20:42
1
This post received
KUDOS
A. A says that the SAME species of fish are reproducing ~50degrees while the passage suggests the same species are not reproducing under the dam with temperature at 6 degrees. so raising the temperature up should get some reproduction going.
_________________

If you like my answers please +1 kudos!

Kudos [?]: 273 [1], given: 52

Director
Director
User avatar
Joined: 25 Aug 2007
Posts: 927

Kudos [?]: 1506 [0], given: 40

WE 1: 3.5 yrs IT
WE 2: 2.5 yrs Retail chain
Re: Emerald River Dam [#permalink]

Show Tags

New post 03 May 2010, 22:21
IMO A.

Premise - Decrease in temp >>> decline in fish population
Conclusion - Rise in temp causes fishes to reproduce.

Let'c check choices:
(A) The native fish species were still able to reproduce only in side streams of the river below the dam where the annual temperature range remains approximately 50 degrees. [Correct. ]

(B) Before the dam was built, the Emerald River annually overflowed its banks, creating backwaters that were critical breeding areas for the native species of fish. [This is OUT OF SCOPE. Incorrect]

(C) The lowest recorded temperature of the Emerald River before the dam was built was 34 degrees, whereas the lowest recorded temperature of the river after the dam was built has been 43 degrees. [This is not showing the temp decrease or temp increase and also reverse to one of the facts - Since the dam reduced the annual range of water temperature in the river below the dam from 50 degrees to 6 degrees. Incorrect]

(D) Nonnative species of fish, introduced into the Emerald River after the dam was built, have begun competing with the declining native fish species for food and space. [Simply a Weaking. It is against scientists' hypothesis. Incorrect]

(E) Five of the fish species native to the Emerald River are not native to any other river in North America. [We dont know how many species. This choice is OUT of SCOPE. Incorrect]

noboru wrote:
Two decades after the Emerald River Dam was built, none of the eight fish species native to the Emerald River was still reproducing adequately in the river below the dam. Since the dam reduced the annual range of water temperature in the river below the dam from 50 degrees to 6 degrees, scientists have hypothesized that sharply rising water temperatures must be involved in signaling the native species to begin the reproductive cycle.

Which of the following statements, if true, would most strengthen the scientists’ hypothesis?
(A) The native fish species were still able to reproduce only in side streams of the river below the dam where the annual temperature range remains approximately 50 degrees.
(B) Before the dam was built, the Emerald River annually overflowed its banks, creating backwaters that were critical breeding areas for the native species of fish.
(C) The lowest recorded temperature of the Emerald River before the dam was built was 34 degrees, whereas the lowest recorded temperature of the river after the dam was built has been 43 degrees.
(D) Nonnative species of fish, introduced into the Emerald River after the dam was built, have begun competing with the declining native fish species for food and space.
(E) Five of the fish species native to the Emerald River are not native to any other river in North America.

_________________

Want to improve your CR: http://gmatclub.com/forum/cr-methods-an-approach-to-find-the-best-answers-93146.html
Tricky Quant problems: http://gmatclub.com/forum/50-tricky-questions-92834.html
Important Grammer Fundamentals: http://gmatclub.com/forum/key-fundamentals-of-grammer-our-crucial-learnings-on-sc-93659.html

Kudos [?]: 1506 [0], given: 40

1 KUDOS received
Manager
Manager
avatar
Joined: 27 Oct 2009
Posts: 141

Kudos [?]: 107 [1], given: 18

Location: Montreal
Schools: Harvard, Yale, HEC
Re: Emerald River Dam [#permalink]

Show Tags

New post 10 Jan 2011, 12:21
1
This post received
KUDOS
I WONDER IF THE TEMP. ACTUALLY DECREASES OR THE RANGE OF TEMP DOES. TRICKY QUESTION.

Kudos [?]: 107 [1], given: 18

Manager
Manager
avatar
Joined: 08 Dec 2010
Posts: 199

Kudos [?]: 54 [0], given: 26

WE 1: 4 yr IT
Re: Emerald River Dam [#permalink]

Show Tags

New post 05 Mar 2011, 13:03
IMO C. the scientists say SHARP RISE in temperature. this can happen only when there is a vast difference between the highest and lowest. best explained by C
_________________

this time, we play for keeps

Kudos [?]: 54 [0], given: 26

1 KUDOS received
Manager
Manager
avatar
Joined: 28 Sep 2011
Posts: 200

Kudos [?]: 93 [1], given: 5

Re: Two decades after the Emerald River Dam was built, none of [#permalink]

Show Tags

New post 21 Mar 2012, 19:14
1
This post received
KUDOS
I picked the answer A:

The conclusion is: [highlight]Scientists have hypothesized that sharply rising water temperatures must be involved in signaling the native species to begin the reproductive cycle.[/highlight]

A. This presents a strong reason to support their hypothesis. You are essentially performing a sensitivity test - you are just changing the temperature range and seeing how the fish react. All the other variables have been kept constant (ie. same fish, same river etc.). Therefore, if the same fish can reproduce in the same river with only a change in the temperature range, that is proof that the dam has changed the reproductive cycle.

B. First, I believe that this point is irrelevant because we are only concerned about the relationship between reproductive cycle in the river below the dam and the temperature of the river. Also, this answer choice could potentially point to another reason why reproductive cycles happened before the dam was built - in this case it would weaken the argument. In either case, this answer is incorrect.

C. This answer choice only gives you 2 specific temperatures. The first question I had was "where were temperatures recorded?" There is no explanation of that in this answer choice, so the temperature readings could actually have been taken before the dam - that would be irrelevant to this question since we are only concerned with the river after the dam. Also, we are only concerned with the RANGE of temperatures and not the temperature itself.

D. This could provide an alternate explanation as to why the fish are not reproducing. Therefore, this answer choice would actually weaken the argument.

E. What does this even tell us? This answer choice is irrelevant.

Kudos [?]: 93 [1], given: 5

Current Student
User avatar
Joined: 06 Sep 2013
Posts: 1978

Kudos [?]: 719 [0], given: 355

Concentration: Finance
GMAT ToolKit User
Re: Emerald River Dam [#permalink]

Show Tags

New post 25 May 2014, 17:36
ezinis wrote:
I WONDER IF THE TEMP. ACTUALLY DECREASES OR THE RANGE OF TEMP DOES. TRICKY QUESTION.


Second that. Is there a catch between range of temperature and actual increase/decrease in temperature?

Cheers
J :)

Kudos [?]: 719 [0], given: 355

Senior Manager
Senior Manager
User avatar
B
Joined: 17 Sep 2013
Posts: 387

Kudos [?]: 339 [0], given: 139

Concentration: Strategy, General Management
GMAT 1: 730 Q51 V38
WE: Analyst (Consulting)
GMAT ToolKit User Premium Member Reviews Badge
Re: Emerald River Dam [#permalink]

Show Tags

New post 26 May 2014, 00:02
jlgdr wrote:
ezinis wrote:
I WONDER IF THE TEMP. ACTUALLY DECREASES OR THE RANGE OF TEMP DOES. TRICKY QUESTION.


Second that. Is there a catch between range of temperature and actual increase/decrease in temperature?

Cheers
J :)



There is no need to wonder over this one..even if the range decrease is true by the measured temps...it is something that the premise states explicitly..So it is just repeating an info that we already know..A dangerous trap in such questions

You might call it a trap though..coz the temperature drop decrease does not imply lower range..what if there was an increase in global temperatures altogether? :-D
_________________

Appreciate the efforts...KUDOS for all
Don't let an extra chromosome get you down..:P

Kudos [?]: 339 [0], given: 139

GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 01 Oct 2013
Posts: 10120

Kudos [?]: 262 [0], given: 0

Premium Member
Re: Two decades after the Emerald River Dam was built, none of [#permalink]

Show Tags

New post 03 Feb 2016, 09:56
Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.

Kudos [?]: 262 [0], given: 0

Intern
Intern
avatar
Joined: 15 Nov 2015
Posts: 47

Kudos [?]: 8 [0], given: 1

Re: Two decades after the Emerald River Dam was built, none of [#permalink]

Show Tags

New post 14 Apr 2016, 12:41
Conclusion: Sharply rising temp signals fish to begin reproductive cycle
Premise: Range decreased from 50 to 6

Premise( say temperature increased from 10 to 60 , rather than from 10 to 16) leads strongly to conclusion. Correct answer will provide examples for the hypothesis.
C just mentions lowest temperatures, nothing new is provided. Lowest recorded before 34, highest 84. Lowest recorded before 43, highest 49. No new evidence. Correct choice for a strengthen question will go slightly out of scope.

Kudos [?]: 8 [0], given: 1

VP
VP
avatar
S
Joined: 09 Jun 2010
Posts: 1403

Kudos [?]: 159 [0], given: 916

Re: Two decades after the Emerald River Dam was built, none of [#permalink]

Show Tags

New post 15 Apr 2016, 01:19
noboru wrote:
Official Guide for GMAT Verbal Review, 2nd Edition

Practice Question
Question No.: 35
Page: 129
Difficulty:


Two decades after the Emerald River Dam was built, none of the eight fish species native to the Emerald River was still reproducing adequately in the river below the dam. Since the dam reduced the annual range of water temperature in the river below the dam from 50 degrees to 6 degrees, scientists have hypothesized that sharply rising water temperatures must be involved in signaling the native species to begin the reproductive cycle.

Which of the following statements, if true, would most strengthen the scientists’ hypothesis?
(A) The native fish species were still able to reproduce only in side streams of the river below the dam where the annual temperature range remains approximately 50 degrees.
(B) Before the dam was built, the Emerald River annually overflowed its banks, creating backwaters that were critical breeding areas for the native species of fish.
(C) The lowest recorded temperature of the Emerald River before the dam was built was 34 degrees, whereas the lowest recorded temperature of the river after the dam was built has been 43 degrees.
(D) Nonnative species of fish, introduced into the Emerald River after the dam was built, have begun competing with the declining native fish species for food and space.
(E) Five of the fish species native to the Emerald River are not native to any other river in North America.


we do not need formal logic to do this problem.
A cause B
no A cause no B because if A exist,we have B. this is formal logic which I dont know and dont need to know
choice A in fact is another facet of arguement. choice A is a strengthener.
_________________

visit my facebook to help me.
on facebook, my name is: thang thang thang

Kudos [?]: 159 [0], given: 916

Manager
Manager
avatar
B
Joined: 18 Sep 2015
Posts: 109

Kudos [?]: 35 [0], given: 612

GMAT 1: 610 Q43 V31
GMAT 2: 610 Q47 V27
GMAT 3: 650 Q48 V31
GMAT 4: 700 Q49 V35
WE: Project Management (Health Care)
GMAT ToolKit User
Re: Two decades after the Emerald River Dam was built, none of [#permalink]

Show Tags

New post 12 May 2016, 04:28
noboru wrote:
Official Guide for GMAT Verbal Review, 2nd Edition

Practice Question
Question No.: 35
Page: 129
Difficulty:


Two decades after the Emerald River Dam was built, none of the eight fish species native to the Emerald River was still reproducing adequately in the river below the dam. Since the dam reduced the annual range of water temperature in the river below the dam from 50 degrees to 6 degrees, scientists have hypothesized that sharply rising water temperatures must be involved in signaling the native species to begin the reproductive cycle.

Which of the following statements, if true, would most strengthen the scientists’ hypothesis?
(A) The native fish species were still able to reproduce only in side streams of the river below the dam where the annual temperature range remains approximately 50 degrees.
(B) Before the dam was built, the Emerald River annually overflowed its banks, creating backwaters that were critical breeding areas for the native species of fish.
(C) The lowest recorded temperature of the Emerald River before the dam was built was 34 degrees, whereas the lowest recorded temperature of the river after the dam was built has been 43 degrees.
(D) Nonnative species of fish, introduced into the Emerald River after the dam was built, have begun competing with the declining native fish species for food and space.
(E) Five of the fish species native to the Emerald River are not native to any other river in North America.


Data:
- Dam built (lets call it X) , Fish did not reproduce enough( Lets call it Y)
- Average annual temp decreased (Lets call it Z)

Notice that we have correlation implied between:
- X & Y
- Z & X
- Z & Y

Conclusion:
- In order to signal (I assume that natures signals) -> the water temp is rising.
--------------------
Assumptions:
- Nature signals to fish to reproduce by rising the water temp
- High enough temp -> fish reproduce

[V] - A - This indeed strengthen one of the assumptions.
[X] - B - This might explain why the overall fish population decreased, by telling us that an essential factor for breeding was not available, but it got nothing with conclusion (temperature is not mentioned).
[X] - C - This choice have no effect. In addition, a signal data point cannot indicate a general trend.
[X] - D - This might explain why the overall fish population decreased by telling us that critical factors for the fish survival was scarce, but it got nothing to do with the conclusion.
[X] - E - Clearly out of scope.

Kudos [?]: 35 [0], given: 612

Manager
Manager
avatar
S
Joined: 03 Jan 2017
Posts: 197

Kudos [?]: 9 [0], given: 4

Re: Two decades after the Emerald River Dam was built, none of [#permalink]

Show Tags

New post 14 Mar 2017, 14:29
that's a Strenghten question: we need to find an answer choice saying that raising temprature would be helpful in increasing the population

Kudos [?]: 9 [0], given: 4

Manager
Manager
User avatar
B
Status: Final Call! Will Achieve Target ANyHow This Tym! :)
Joined: 05 Jan 2016
Posts: 92

Kudos [?]: 5 [0], given: 135

Location: India
GMAT 1: 620 Q49 V25
GPA: 3.8
Reviews Badge CAT Tests
Re: Two decades after the Emerald River Dam was built, none of [#permalink]

Show Tags

New post 07 Aug 2017, 09:25
Two decades after the Emerald River Dam was built, none of the eight fish species native to the Emerald River was still reproducing adequately in the river below the dam. Since the dam reduced the annual range of water temperature in the river below the dam from 50 degrees to 6 degrees, scientists have hypothesized that sharply rising water temperatures must be involved in signaling the native species to begin the reproductive cycle.

Which of the following statements, if true, would most strengthen the scientists’ hypothesis?

(A) The native fish species were still able to reproduce only in side streams of the river below the dam where the annual temperature range remains approximately 50 degrees.
This supports what scientists have hypothesized.

(B) Before the dam was built, the Emerald River annually overflowed its banks, creating backwaters that were critical breeding areas for the native species of fish.
This option suggests that after the dam was built, Emerald river could not overflow and thus no backwaters created, thus it provides another cause for the breeding inadequacy of the native fish species of the Emerald river. It weakens.
Choice B undermines the hypothesis by suggesting a completely different hypothesis;

(C) The lowest recorded temperature of the Emerald River before the dam was built was 34 degrees, whereas the lowest recorded temperature of the river after the dam was built has been 43 degrees.
The argument is talking about the annual range of temperature, but this option is talking about the lowest recorded temperature. Therefore, just on the basis of lowest recorded temperature we cannot comment on the hypothesis of the scientists.

(D) Non-native species of fish, introduced into the Emerald River after the dam was built, have begun competing with the declining native fish species for food and space.
This option D relates a development after the native species began to decline, it does not bear on the hypothesis, which concerns the decline’s original cause;

(E) Five of the fish species native to the Emerald River are not native to any other river in North America.
Irrelevant. This option statement has no impact on the above scientist's hypothesis.

Can someone explain option C in more detail
_________________

Regards,
Varun


Trying my best..... will succeed definitely! :)

The Moment You Think About Giving Up, Think Of The Reason Why You Held On So Long.
+1 Kudos if you find this post helpful. :)

Do Check OG 2017 SC Solutions - http://gmatwithcj.com/solutions-gmat-official-guide-2017-sentence-correction-questions/

Kudos [?]: 5 [0], given: 135

Mannheim Thread Master
User avatar
S
Status: It's now or never
Joined: 10 Feb 2017
Posts: 276

Kudos [?]: 27 [0], given: 51

Location: India
GMAT 1: 650 Q40 V39
GPA: 3
WE: Consulting (Consulting)
GMAT ToolKit User
Re: Two decades after the Emerald River Dam was built, none of [#permalink]

Show Tags

New post 17 Aug 2017, 03:22
Correct choice is 'A' - The construction of a dam has significantly reduced the range of water temperatures in the river below the dam. Scientists have implicated this change in the failure of native fish species to reproduce adequately. Hence, statement 'A' strengthen Scientists' hypothesis.
_________________

2017-2018 MBA Deadlines

Threadmaster for B-school Discussions
Class of 2019: Mannheim Business School
Class 0f 2020: HHL Leipzig

Kudos [?]: 27 [0], given: 51

Manager
Manager
avatar
S
Joined: 05 Jul 2017
Posts: 153

Kudos [?]: 31 [0], given: 162

Location: India
Concentration: Entrepreneurship, Technology
GMAT 1: 700 Q49 V36
Re: Two decades after the Emerald River Dam was built, none of [#permalink]

Show Tags

New post 22 Sep 2017, 08:33
Hello GMATNinja

Can you explain A vs C?

Quote:
C. The lowest recorded temperature of the Emerald River before the dam was built was 34 degrees, whereas the lowest recorded temperature of the river after the dam was built has been 43 degrees.


Is C wrong because it doesn't mention that these lowest temperatures were of the river below the dam? It just mentions the lowest temperatures in general of the entire river

Quote:
A. The native fish species were still able to reproduce only in side streams of the river below the dam where the annual temperature range remains approximately 50 degrees.


Although Option A mentions that the range is approximately same, we don't know whether the side stream has the exact same temperatures. Let me put down an example to make it clear
1. Temperature range of the river below the dam before the dam was built : 60 degree to 10 Degree
2. Temperature range of the river below the dam after the dam was built : 26 degree to 20 degree
3. Temperature range of the side streams below the dam after the dam was built : 10 degree to -40 degree

If you see #3 - the range is same but reproduction may depend on the rising temperatures that were attained in case #1. So may weaken the conclusion or strengthen

I think there is a very small difference between A and C. Let me know your thoughts

Kudos [?]: 31 [0], given: 162

Intern
Intern
User avatar
B
Status: Retaking GMAT
Joined: 21 Oct 2012
Posts: 18

Kudos [?]: 11 [0], given: 29

Location: India
Concentration: General Management, Technology
GMAT 1: 680 Q50 V30
GMAT 2: 710 Q51 V34
GMAT 3: 730 Q50 V38
GPA: 3.8
WE: General Management (Other)
CAT Tests
Re: Two decades after the Emerald River Dam was built, none of [#permalink]

Show Tags

New post 24 Sep 2017, 23:19
Here, we are supposed to strengthen the hypothesis - Sharply Rising Water temperatures trigger reproduction cycle.

However, Option A just highlights that reproduction is happening because the temperature range is 50 degrees. It doesn't imply that it is the SHARPLY RISING TEMPERATURE that is causing the reproduction. It may be the SHARP REDUCTION in temperature that triggers the reproduction cycle, or it may be a particular temperature which triggers the reproduction(which the current 6 degrees range is not allowing the water to reach).

I marked C, because it atleast talks about the water temperatures which is pertinent to the hypothesis.

Kudos [?]: 11 [0], given: 29

Re: Two decades after the Emerald River Dam was built, none of   [#permalink] 24 Sep 2017, 23:19
Display posts from previous: Sort by

Two decades after the Emerald River Dam was built, none of

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

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®.