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

 It is currently 08 Dec 2019, 17:20

### 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

# Manufacturers of motor oil for car engines have found

Author Message
TAGS:

### Hide Tags

Senior Manager
Status: 1,750 Q's attempted and counting
Affiliations: University of Florida
Joined: 09 Jul 2013
Posts: 474
Location: United States (FL)
Schools: UFL (A)
GMAT 1: 600 Q45 V29
GMAT 2: 590 Q35 V35
GMAT 3: 570 Q42 V28
GMAT 4: 610 Q44 V30
GPA: 3.45
WE: Accounting (Accounting)
Manufacturers of motor oil for car engines have found  [#permalink]

### Show Tags

23 Nov 2013, 14:24
1
2
00:00

Difficulty:

35% (medium)

Question Stats:

69% (01:38) correct 31% (01:59) wrong based on 464 sessions

### HideShow timer Statistics

Manufacturers of motor oil for car engines have found through research that motor oil slowly loses lubrication effectiveness after the car is driven for certain distances. On average, the motor oil is only fifty percent as effective after 3,000 miles of driving as it is the first day it is put into the car. For that reason, people should replace their motor oil every 3,000 miles.

Which of the following, if true, would most weaken the conclusion above?

(A) The research indicates that the oil loses effectiveness because it becomes dirty.
(B) The researchers found that there was not a significant difference in the effectiveness of motor oil in cars that reached 3,000 miles quickly versus those that took a long time to reach 3,000 miles.
(C) The researchers found that cars with motor oil at fifty percent effectiveness showed no more signs of damage or wear than those with fresh motor oil.
(D) The researchers were paid by the manufacturers of motor oil, who have a vested interest in selling more motor oil.
(E) Both synthetic and non-synthetic motor oils experience similar losses in motor oil effectiveness after 3,000 miles of driving.

OE to follow
Senior Manager
Status: 1,750 Q's attempted and counting
Affiliations: University of Florida
Joined: 09 Jul 2013
Posts: 474
Location: United States (FL)
Schools: UFL (A)
GMAT 1: 600 Q45 V29
GMAT 2: 590 Q35 V35
GMAT 3: 570 Q42 V28
GMAT 4: 610 Q44 V30
GPA: 3.45
WE: Accounting (Accounting)
Re: Manufacturers of motor oil for car engines have found  [#permalink]

### Show Tags

28 Nov 2013, 21:47

Official Explanation

Answer C - In this argument, the conclusion is that people should change their motor oil every 3,000 miles. The conclusion is based on the fact that motor oil loses half of its effectiveness after being driven that distance. The central assumption here is that the loss of effectiveness is indeed a valid reason for changing the motor oil. Choice (C) challenges this assumption by saying that cars with motor oil at fifty percent effectiveness do not have any ill effects. Thus, choice (C) is the correct answer.

Choices (A), (B), and (E) are all out of scope. The fact that oil loses effectiveness because it becomes dirty does not weaken the conclusion. It also does not matter that cars that reach 3,000 miles at different rates experience similar declines in motor oil effectiveness; it also does not matter that the same is true of cars with different types of motor oil.

Choice (D) may be tempting, but is ultimately irrelevant. We may want to gravitate to a choice like (D) that questions the motives for the research, however we never want to challenge the evidence itself in a weaken question – only the central assumption. Even though the research was conducted under the supervision of motor oil companies, this does not alone weaken the conclusion that motor oil should be changed every 3,000 miles.
Intern
Joined: 11 Nov 2013
Posts: 21
Re: Manufacturers of motor oil for car engines have found  [#permalink]

### Show Tags

28 Nov 2013, 23:27
[quote="avohden"]Manufacturers of motor oil for car engines have found through research that motor oil slowly loses lubrication effectiveness after the car is driven for certain distances. On average, the motor oil is only fifty percent as effective after 3,000 miles of driving as it is the first day it is put into the car. For that reason, people should replace their motor oil every 3,000 miles.

Which of the following, if true, would most weaken the conclusion above?

(A) The research indicates that the oil loses effectiveness because it becomes dirty.
(B) The researchers found that there was not a significant difference in the effectiveness of motor oil in cars that reached 3,000 miles quickly versus those that took a long time to reach 3,000 miles.
(C) The researchers found that cars with motor oil at fifty percent effectiveness showed no more signs of damage or wear than those with fresh motor oil.
(D) The researchers were paid by the manufacturers of motor oil, who have a vested interest in selling more motor oil.
(E) Both synthetic and non-synthetic motor oils experience similar losses in motor oil effectiveness after 3,000 miles of driving.

Hello Dear,
the effectiveness of 50 percent is after every 3000 miles ia right think about engine oil..but if we can't change it then engine power is slightly fall down after some time..
I know option C is right but it is not applicable for every engine oil..
Manager
Joined: 11 Sep 2016
Posts: 50
Location: Azerbaijan
Concentration: Finance, General Management
GMAT 1: 570 Q44 V27
GPA: 3.11
WE: Other (Consulting)
Re: Manufacturers of motor oil for car engines have found  [#permalink]

### Show Tags

28 Nov 2016, 05:09
surajkumar00116 wrote:
avohden wrote:
Manufacturers of motor oil for car engines have found through research that motor oil slowly loses lubrication effectiveness after the car is driven for certain distances. On average, the motor oil is only fifty percent as effective after 3,000 miles of driving as it is the first day it is put into the car. For that reason, people should replace their motor oil every 3,000 miles.

Which of the following, if true, would most weaken the conclusion above?

(A) The research indicates that the oil loses effectiveness because it becomes dirty.
(B) The researchers found that there was not a significant difference in the effectiveness of motor oil in cars that reached 3,000 miles quickly versus those that took a long time to reach 3,000 miles.
(C) The researchers found that cars with motor oil at fifty percent effectiveness showed no more signs of damage or wear than those with fresh motor oil.
(D) The researchers were paid by the manufacturers of motor oil, who have a vested interest in selling more motor oil.
(E) Both synthetic and non-synthetic motor oils experience similar losses in motor oil effectiveness after 3,000 miles of driving.

Hello Dear,
the effectiveness of 50 percent is after every 3000 miles ia right think about engine oil..but if we can't change it then engine power is slightly fall down after some time..
I know option C is right but it is not applicable for every engine oil..

It shouldn't be applicable to all types of engines, because premise states "On average, the motor oil is only fifty percent as effective after 3,000 miles of driving as it is the first day it is put into the car"
Intern
Joined: 04 Nov 2015
Posts: 8
Manufacturers of motor oil for car engines have found through research  [#permalink]

### Show Tags

18 Dec 2016, 03:53
1
1
Manufacturers of motor oil for car engines have found through research that motor oil slowly loses lubrication effectiveness after the car is driven for certain distances. On average, the motor oil is only fifty percent as effective after 3,000 miles of driving as it is the first day it is put into the car. For that reason, people should replace their motor oil every 3,000 miles.

Which of the following, if true, would most weaken the conclusion above?

A) The research indicates that the oil loses effectiveness because it becomes dirty.
B) The researchers found that there was not a significant difference in the effectiveness of motor oil in cars that reached 3,000 miles quickly versus those that took a long time to reach 3,000 miles.
C) The researchers found that cars with motor oil at fifty percent effectiveness showed no more signs of damage or wear than those with fresh motor oil.
D) The researchers were paid by the manufacturers of motor oil, who have a vested interest in selling more motor oil.
E) Both synthetic and non-synthetic motor oils experience similar losses in motor oil effectiveness after 3,000 miles of driving.

PLS EXPLAIN
Current Student
Joined: 28 Nov 2014
Posts: 818
Concentration: Strategy
Schools: Fisher '19 (M\$)
GPA: 3.71
Re: Manufacturers of motor oil for car engines have found through research  [#permalink]

### Show Tags

18 Dec 2016, 05:51
@vikkimba17 Would you like to elaborate on your doubt? It looks like the process of elimination is quite easy and you can get rid of incorrect choices easily.

Sent from my GT-N7100 using GMAT Club Forum mobile app
Retired Moderator
Joined: 14 Dec 2013
Posts: 2849
Location: Germany
Schools: German MBA
GMAT 1: 780 Q50 V47
WE: Corporate Finance (Pharmaceuticals and Biotech)
Re: Manufacturers of motor oil for car engines have found through research  [#permalink]

### Show Tags

19 Dec 2016, 12:06
In my opinion C is not an undebatable answer. It is possible that the damage starts to take place when the effectiveness drops below 50%. Therefore, though at 50% effectiveness the damage is equivalent to that with fresh oil, the oil should be replaced when the effectiveness reaches 50% to avoid damage to the vehicle.
Manager
Joined: 27 Aug 2016
Posts: 87
Location: India
Schools: HEC Montreal '21
GMAT 1: 670 Q47 V37
GPA: 3
WE: Engineering (Energy and Utilities)
Manufacturers of motor oil for car engines have found  [#permalink]

### Show Tags

20 Dec 2016, 11:57
avohden wrote:

Official Explanation

Answer C - In this argument, the conclusion is that people should change their motor oil every 3,000 miles. The conclusion is based on the fact that motor oil loses half of its effectiveness after being driven that distance. The central assumption here is that the loss of effectiveness is indeed a valid reason for changing the motor oil. Choice (C) challenges this assumption by saying that cars with motor oil at fifty percent effectiveness do not have any ill effects. Thus, choice (C) is the correct answer.

Choices (A), (B), and (E) are all out of scope. The fact that oil loses effectiveness because it becomes dirty does not weaken the conclusion. It also does not matter that cars that reach 3,000 miles at different rates experience similar declines in motor oil effectiveness; it also does not matter that the same is true of cars with different types of motor oil.

Choice (D) may be tempting, but is ultimately irrelevant. We may want to gravitate to a choice like (D) that questions the motives for the research, however we never want to challenge the evidence itself in a weaken question – only the central assumption. Even though the research was conducted under the supervision of motor oil companies, this does not alone weaken the conclusion that motor oil should be changed every 3,000 miles.
ot.

Please explain further why not D? A flawed research with vested interests directly strikes out the first statement. Had there been an honest research probably the result would have been that there was no loss of lubrication.
Manager
Joined: 02 Nov 2013
Posts: 67
Location: India
Re: Manufacturers of motor oil for car engines have found  [#permalink]

### Show Tags

22 Dec 2016, 09:26
Here is my explanation for the argument,
(A) The research indicates that the oil loses effectiveness because it becomes dirty. ----- There is no information about oil getting dirty in the argument.
(B) The researchers found that there was not a significant difference in the effectiveness of motor oil in cars that reached 3,000 miles quickly versus those that took a long time to reach 3,000 miles. ----- time to reach the 3000 miles does not effect the performance of the oil... Not correct
(C) The researchers found that cars with motor oil at fifty percent effectiveness showed no more signs of damage or wear than those with fresh motor oil. ----- Correct, Proves that even after fifty percent effectiveness shows signs equivalent to fresh motor oil..
(D) The researchers were paid by the manufacturers of motor oil, who have a vested interest in selling more motor oil.---
(E) Both synthetic and non-synthetic motor oils experience similar losses in motor oil effectiveness after 3,000 miles of driving.---- categorization of motor oil in synthetic and non synthetic is not available in the argument.
Manager
Joined: 04 Jun 2015
Posts: 77
Re: Manufacturers of motor oil for car engines have found  [#permalink]

### Show Tags

27 Dec 2016, 01:29
avohden wrote:
Manufacturers of motor oil for car engines have found through research that motor oil slowly loses lubrication effectiveness after the car is driven for certain distances. On average, the motor oil is only fifty percent as effective after 3,000 miles of driving as it is the first day it is put into the car. For that reason, people should replace their motor oil every 3,000 miles.

Which of the following, if true, would most weaken the conclusion above?

(A) The research indicates that the oil loses effectiveness because it becomes dirty.
(B) The researchers found that there was not a significant difference in the effectiveness of motor oil in cars that reached 3,000 miles quickly versus those that took a long time to reach 3,000 miles.
(C) The researchers found that cars with motor oil at fifty percent effectiveness showed no more signs of damage or wear than those with fresh motor oil.
(D) The researchers were paid by the manufacturers of motor oil, who have a vested interest in selling more motor oil.
(E) Both synthetic and non-synthetic motor oils experience similar losses in motor oil effectiveness after 3,000 miles of driving.

I was stuck between B and C. But ultimately chose B.
I reasoned B as the right one because B says there is no significant difference in effectiveness of the oil that reached 3000 miles (the claimed time to change the oil) vs. oil that took time to reach 3000 miles (the oil present from the moment it was put in). So if there is no significant difference in effectiveness then it doesn't make any sense changing the oil after 3000 miles (since the car is claimed to run normally when the oil is initially put in).

_________________
Sortem sternit fortem!
Director
Joined: 08 Jun 2013
Posts: 542
Location: France
GMAT 1: 200 Q1 V1
GPA: 3.82
WE: Consulting (Other)
Re: Manufacturers of motor oil for car engines have found  [#permalink]

### Show Tags

17 Dec 2018, 03:06
The question directly asks for something that weakens the argument, making this a Weaken question.

The author concludes that motor oil should be changed every 3,000 miles, because after 3,000 miles it is only 50% effective.

The author is assuming that, once oil becomes only 50% effective, it needs to be changed. The correct choice will counter that assumption, showing that there it may not be necessary to replace motor oil when it becomes only 50% effective.

(C) matches the prediction and is correct. If 50% effectiveness is enough to match the performance of fresh oil in preventing engine wear, this makes it less likely oil would have to be replaced at 3,000 miles.

(A) is irrelevant. The author is not concerned with why the oil loses its effectiveness but whether that loss warrants changing the oil.

(B) is irrelevant. It does not matter how long it takes to reach the 3,000-mile threshold. The only question is whether or not the oil needs to be changed at that point.

(D) may be tempting, but it is irrelevant. A choice like (D) that questions the motives for the research may seem to weaken the argument. However, the evidence in a Weaken question can never be challenged - only the central assumption. Who supervised the research is not an issue. The argument is only concerned with the reduction in effectiveness and the recommendation to replace motor oil after 3,000 miles.

(E) is an irrelevant comparison between two types of oil and has no effect on the argument.
_________________
Everything will fall into place…

There is perfect timing for
everything and everyone.
Never doubt, But Work on
improving yourself,
Keep the faith and
It will all make sense.
Re: Manufacturers of motor oil for car engines have found   [#permalink] 17 Dec 2018, 03:06
Display posts from previous: Sort by