The level of lead contamination in United States rivers : GMAT Critical Reasoning (CR)
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 23 Jan 2017, 12:32

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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

The level of lead contamination in United States rivers

Author Message
TAGS:

Hide Tags

Director
Joined: 01 Aug 2008
Posts: 768
Followers: 4

Kudos [?]: 626 [0], given: 99

Show Tags

18 Mar 2009, 14:43
1
This post was
BOOKMARKED
00:00

Difficulty:

(N/A)

Question Stats:

75% (03:26) correct 25% (02:34) wrong based on 15 sessions

HideShow timer Statistics

The level of lead contamination in United States rivers declined between 1975 and 1985. Federal regulations requiring a drop in industrial discharges of lead went into effect in 1975, but the major cause of the decline was a 75 percent drop in the use of leaded gasoline between 1975 and 1985.
Which of the following, if true, best supports the claim that the major cause of the decline in the level of lead contamination in United States rives was the decline in the use of leaded gasoline?
(A) The level of lead contamination in United States rivers fell sharply in both 1975 and 1983.
(B) Most of the decline in industrial discharges of lead occurred before 1976, but the largest decline in the level of river contamination occurred between 1980 and 1985.
(C) Levels of lead contamination in rivers fell sharply in 1975-1976 and rose very slightly over the next nine years.
(D) Levels of lead contamination rose in those rivers where there was reduced river flow due to drought.
(E) Although the use of leaded gasoline declined 75 percent between 1975 and 1985, 80 percent of the decline took place in 1985.
If you have any questions
New!
SVP
Joined: 04 May 2006
Posts: 1926
Schools: CBS, Kellogg
Followers: 23

Kudos [?]: 1013 [0], given: 1

Show Tags

18 Mar 2009, 19:43
ugimba wrote:
The level of lead contamination in United States rivers declined between 1975 and 1985. Federal regulations requiring a drop in industrial discharges of lead went into effect in 1975, but the major cause of the decline was a 75 percent drop in the use of leaded gasoline between 1975 and 1985.
Which of the following, if true, best supports the claim that the major cause of the decline in the level of lead contamination in United States rives was the decline in the use of leaded gasoline?
(A) The level of lead contamination in United States rivers fell sharply in both 1975 and 1983.
(B) Most of the decline in industrial discharges of lead occurred before 1976, but the largest decline in the level of river contamination occurred between 1980 and 1985.
(C) Levels of lead contamination in rivers fell sharply in 1975-1976 and rose very slightly over the next nine years.
(D) Levels of lead contamination rose in those rivers where there was reduced river flow due to drought.
(E) Although the use of leaded gasoline declined 75 percent between 1975 and 1985, 80 percent of the decline took place in 1985.

E is the best
_________________
Director
Joined: 04 Jan 2008
Posts: 912
Followers: 69

Kudos [?]: 574 [0], given: 17

Show Tags

18 Mar 2009, 22:07
why not B?
Its saying
Most of the decline in industrial discharges of lead occurred before 1976, but the largest decline in the level of river contamination occurred between 1980 and 1985.
_________________

http://gmatclub.com/forum/math-polygons-87336.html
http://gmatclub.com/forum/competition-for-the-best-gmat-error-log-template-86232.html

Director
Joined: 01 Apr 2008
Posts: 897
Name: Ronak Amin
Schools: IIM Lucknow (IPMX) - Class of 2014
Followers: 28

Kudos [?]: 648 [0], given: 18

Show Tags

18 Mar 2009, 22:39
For me B. What is OA?

B because even before 1976 discharges declined, still the contamination level didnt reduce much, however only during 1975-85 major decline in contamination happened, which means there was another major cause for this decline in contamination => decline in the gasoline usage.

Not E, because E talks about the decline in the use of gasoline and not about the decilne in the lead contamination level, there doesnt seem to be any link. Also it boils down to 1985 which doest help much.

sondenso wrote:
ugimba wrote:
The level of lead contamination in United States rivers declined between 1975 and 1985. Federal regulations requiring a drop in industrial discharges of lead went into effect in 1975, but the major cause of the decline was a 75 percent drop in the use of leaded gasoline between 1975 and 1985.
Which of the following, if true, best supports the claim that the major cause of the decline in the level of lead contamination in United States rives was the decline in the use of leaded gasoline?
(A) The level of lead contamination in United States rivers fell sharply in both 1975 and 1983.
(B) Most of the decline in industrial discharges of lead occurred before 1976, but the largest decline in the level of river contamination occurred between 1980 and 1985.
(C) Levels of lead contamination in rivers fell sharply in 1975-1976 and rose very slightly over the next nine years.
(D) Levels of lead contamination rose in those rivers where there was reduced river flow due to drought.
(E) Although the use of leaded gasoline declined 75 percent between 1975 and 1985, 80 percent of the decline took place in 1985.

E is the best
Director
Joined: 01 Aug 2008
Posts: 768
Followers: 4

Kudos [?]: 626 [0], given: 99

Show Tags

19 Mar 2009, 19:21
OA is B. I chose E though ..

thanks all.
Manager
Joined: 05 Dec 2009
Posts: 127
Followers: 2

Kudos [?]: 87 [0], given: 0

Show Tags

13 Mar 2010, 12:30
for me B
Manhattan GMAT Instructor
Affiliations: ManhattanGMAT
Joined: 21 Jan 2010
Posts: 354
Location: San Francisco
Followers: 497

Kudos [?]: 1316 [3] , given: 11

Show Tags

14 Mar 2010, 11:16
3
KUDOS
Hey All,

Seems to be a bit of back and forth on this, so I thought I'd try to take it on using the (dreaded) process. I know, I know. Nothing's less fun then taking notes...but let's do it anyway:

Conclusion: Major cause of decline in LC was decline in lead gas [It's pretty common to find the conclusion in the question stem...so always be on the lookout]

Premises: Decline between 75 and 85. Feds said industrial discharge down in 1975. 75% drop in lead gasoline between 75 and 85.

Assumption: Industrial discharge didn't do it. [Basically, we're looking for something to downplay the importance of the legislation.]

(A) The level of lead contamination in United States rivers fell sharply in both 1975 and 1983.
PROBLEM: This would possibly weaken. We wouldn't want to see sharp declines, because it sounds like the drop was gradual (as lead gas was phased out).

(B) Most of the decline in industrial discharges of lead occurred before 1976, but the largest decline in the level of river contamination occurred between 1980 and 1985.
ANSWER: Well, if the industrial decline occurred before 1976, that means that the effect of the legislation was almost immediate. But if the contamination dropped mostly between 80 and 85, that could only be because of the rise of unleaded gas.

(C) Levels of lead contamination in rivers fell sharply in 1975-1976 and rose very slightly over the next nine years.
PROBLEM: This weakens a lot. This sounds like the legislation had a big effect, and then nothing happened for the rest of the time. We wanted gas to slowly make things better, but they're actually getting worse!

(D) Levels of lead contamination rose in those rivers where there was reduced river flow due to drought.
PROBLEM: This doesn't connect to either industry or gas, so it's irrelevant.

(E) Although the use of leaded gasoline declined 75 percent between 1975 and 1985, 80 percent of the decline took place in 1985.
PROBLEM: Alright. Here's the toughie. The problem is that this doesn't actually add any information that we didn't have in the passage itself. Looks like it does, doesn't it? But think about it. We already knew the use of leaded gasoline declined 75 percent between 75 and 85 (that part is LITERALLY in the passage word for word). Then we're just told that most of it happened at the end. So what? That doesn't tell us anything about the contamination itself. What we really wanted was to WEAKEN the influence of the legislation, which B does.

Hope that helps!

-t
_________________

Tommy Wallach | Manhattan GMAT Instructor | San Francisco

Manhattan GMAT Discount | Manhattan GMAT Reviews

VP
Status: Final Lap Up!!!
Affiliations: NYK Line
Joined: 21 Sep 2012
Posts: 1096
Location: India
GMAT 1: 410 Q35 V11
GMAT 2: 530 Q44 V20
GMAT 3: 630 Q45 V31
GPA: 3.84
WE: Engineering (Transportation)
Followers: 37

Kudos [?]: 527 [0], given: 70

Show Tags

27 Oct 2012, 00:47
TommyWallach wrote:
Hey All,

Seems to be a bit of back and forth on this, so I thought I'd try to take it on using the (dreaded) process. I know, I know. Nothing's less fun then taking notes...but let's do it anyway:

Conclusion: Major cause of decline in LC was decline in lead gas [It's pretty common to find the conclusion in the question stem...so always be on the lookout]

Premises: Decline between 75 and 85. Feds said industrial discharge down in 1975. 75% drop in lead gasoline between 75 and 85.

Assumption: Industrial discharge didn't do it. [Basically, we're looking for something to downplay the importance of the legislation.]

(A) The level of lead contamination in United States rivers fell sharply in both 1975 and 1983.
PROBLEM: This would possibly weaken. We wouldn't want to see sharp declines, because it sounds like the drop was gradual (as lead gas was phased out).

(B) Most of the decline in industrial discharges of lead occurred before 1976, but the largest decline in the level of river contamination occurred between 1980 and 1985.
ANSWER: Well, if the industrial decline occurred before 1976, that means that the effect of the legislation was almost immediate. But if the contamination dropped mostly between 80 and 85, that could only be because of the rise of unleaded gas.

(C) Levels of lead contamination in rivers fell sharply in 1975-1976 and rose very slightly over the next nine years.
PROBLEM: This weakens a lot. This sounds like the legislation had a big effect, and then nothing happened for the rest of the time. We wanted gas to slowly make things better, but they're actually getting worse!

(D) Levels of lead contamination rose in those rivers where there was reduced river flow due to drought.
PROBLEM: This doesn't connect to either industry or gas, so it's irrelevant.

(E) Although the use of leaded gasoline declined 75 percent between 1975 and 1985, 80 percent of the decline took place in 1985.
PROBLEM: Alright. Here's the toughie. The problem is that this doesn't actually add any information that we didn't have in the passage itself. Looks like it does, doesn't it? But think about it. We already knew the use of leaded gasoline declined 75 percent between 75 and 85 (that part is LITERALLY in the passage word for word). Then we're just told that most of it happened at the end. So what? That doesn't tell us anything about the contamination itself. What we really wanted was to WEAKEN the influence of the legislation, which B does.

Hope that helps!

-t

HI Tommy

I am facing difficulty in understanding assumption which you have considered..request you to pls elaborate it.
GMAT Club Legend
Joined: 01 Oct 2013
Posts: 10542
Followers: 919

Kudos [?]: 204 [0], given: 0

Show Tags

08 May 2015, 11:31
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.
Re: The level of lead contamination in United States rivers   [#permalink] 08 May 2015, 11:31
Similar topics Replies Last post
Similar
Topics:
The level of lead contamination in United States rivers 8 03 Sep 2008, 19:42
2 The United States consumption 5 26 Jan 2008, 11:59
It is not correct that the people of the United States, 5 04 Jul 2007, 17:49
The level of lead contamination in United States rivers 3 13 Mar 2007, 18:29
It is not correct that the people of the United States, 4 12 Mar 2007, 20:01
Display posts from previous: Sort by