The Lichtenstein night adder

This topic has expert replies
User avatar
Junior | Next Rank: 30 Posts
Posts: 25
Joined: Fri Nov 11, 2016 9:44 pm

The Lichtenstein night adder

by gkkk » Tue Mar 07, 2017 6:56 pm
The Lichtenstein night adder, a species of snake, drives away Silver-spotted Skipper insects and takes their nests for its own. When such a nest is destroyed, the adders wander, never spending consecutive days in the same place, until they come across another nest of the Silver-spotted Skipper insect. Clearly, the Lichtenstein night adder does not know how to make nests of its own.

Which of the following, if true, most strengthens the argument?

A. Many sub-species of the adder are known to make their own nests from scratch.
B. In the summer months, the Lichtenstein night adder snake prefers sleeping by hanging from a tree and not staying anywhere on the ground level.
C. In Nigram and Tenitol, countries where Silver-spotted Skippers are not found, the Lichtenstein night adder makes its home in the nests of Cicada insects.
D. The two species of snakes that are closely related to the Lichtenstein night adder species do not live in nests at all.
E. There are no significant differences between the nest of a Silver-spotted Skipper insect and that of some species of adder snakes that make nests of their own.

OA - C

this option seems to be strengthening the argument not weakening it. I selected D
reasoning for D is that no species of such snakes believe in concept of their own nest. others cant be the option even remotely.

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

by Brent@GMATPrepNow » Tue Mar 14, 2017 11:11 am
gkkk wrote:The Lichtenstein night adder, a species of snake, drives away Silver-spotted Skipper insects and takes their nests for its own. When such a nest is destroyed, the adders wander, never spending consecutive days in the same place, until they come across another nest of the Silver-spotted Skipper insect. Clearly, the Lichtenstein night adder does not know how to make nests of its own.

Which of the following, if true, most strengthens the argument?

A. Many sub-species of the adder are known to make their own nests from scratch.
B. In the summer months, the Lichtenstein night adder snake prefers sleeping by hanging from a tree and not staying anywhere on the ground level.
C. In Nigram and Tenitol, countries where Silver-spotted Skippers are not found, the Lichtenstein night adder makes its home in the nests of Cicada insects.
D. The two species of snakes that are closely related to the Lichtenstein night adder species do not live in nests at all.
E. There are no significant differences between the nest of a Silver-spotted Skipper insect and that of some species of adder snakes that make nests of their own.

OA - C

this option seems to be strengthening the argument not weakening it. I selected D
reasoning for D is that no species of such snakes believe in concept of their own nest. others cant be the option even remotely.
Premise: Lichtenstein adder steals a certain insect's nest
Premise: When a stolen nest is destroyed, the adder wanders until finding/stealing another nest
Conclusion: The adder can't make its own nest

We're looking for a new premise that strengthens the conclusion that the adder can't make its own nest.

A) Weakens the conclusion - ELIMINATE
B) Irrelevant since it has nothing to do with next-making- ELIMINATE
C) In the absence of one insect's nest, the snake steals a different insect's nest. This suggests that the snake might not know how to build its own nest - KEEP
D) The conclusion is about the Lichtenstein adder - ELIMINATE
E) This suggests that Lichtenstein adders CAN make their own nests. This weakens the conclusion - ELIMINATE

Answer: C
Brent Hanneson - Creator of GMATPrepNow.com
Image

User avatar
Junior | Next Rank: 30 Posts
Posts: 25
Joined: Fri Nov 11, 2016 9:44 pm

by gkkk » Wed Mar 15, 2017 5:32 am
Thanks for your reply sir.

I have a question here or rather an alternative reasoning. Suppose i know how to build house, but i can buy one too. and if i bought one then is it means that i can't build one. i am still not convinced that This option is really making sure that he don't know how to make a nest.

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

by Brent@GMATPrepNow » Wed Mar 15, 2017 6:52 am
gkkk wrote:Thanks for your reply sir.

I have a question here or rather an alternative reasoning. Suppose i know how to build house, but i can buy one too. and if i bought one then is it means that i can't build one. i am still not convinced that This option is really making sure that he don't know how to make a nest.
Good question.

In strengthen the argument questions, our goal is not to find a premise that guarantees the conclusion. Our goal is to find a premise that strengthens the conclusion. So, if we add to your argument the following:

- I can make a nest or rent a nest, so I choose to rent a nest

The conclusion is strengthened ever so slightly.
In some cases, you might have two premises that strengthen the conclusion, in which case you'll have to determine which one strengthens the conclusion the most.

In the original question, answer choice C is the only one that strengthens the conclusion (ever so slightly), so it is the correct answer.

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image

Master | Next Rank: 500 Posts
Posts: 186
Joined: Sat Dec 24, 2016 12:38 am
Thanked: 5 times
Followed by:3 members

by rsarashi » Sat Jun 03, 2017 5:31 pm
A) Weakens the conclusion - ELIMINATE
Hi Brent ,

Just a quick question, can you please explain that how option A is weaken the conclusion?

Thanks.

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

by Brent@GMATPrepNow » Sun Jun 04, 2017 5:20 am
rsarashi wrote:
A) Weakens the conclusion - ELIMINATE
Hi Brent ,

Just a quick question, can you please explain that how option A is weaken the conclusion?

Thanks.
You bet.

The author's conclusion is that the adder can't make its own nest

Answer choice A says "Many sub-species of the adder are known to make their own nests from scratch. "

Now there are two reasons to eliminate A. One is that, if the adder's related sub-species CAN make a nest, how certain are we that the adder CANNOT make a nest? This potentially could weaken the conclusion. Alternatively, we could just say that this information about a different type of snake has no effect on the conclusion about the adder. In other words, the information certainly does not strengthen the argument.

In either case, we can eliminate A.

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image

Master | Next Rank: 500 Posts
Posts: 186
Joined: Sat Dec 24, 2016 12:38 am
Thanked: 5 times
Followed by:3 members

by rsarashi » Mon Jun 05, 2017 1:39 am
You bet.

The author's conclusion is that the adder can't make its own nest

Answer choice A says "Many sub-species of the adder are known to make their own nests from scratch. "

Now there are two reasons to eliminate A. One is that, if the adder's related sub-species CAN make a nest, how certain are we that the adder CANNOT make a nest? This potentially could weaken the conclusion. Alternatively, we could just say that this information about a different type of snake has no effect on the conclusion about the adder. In other words, the information certainly does not strengthen the argument.

In either case, we can eliminate A.
Hi Brent ,

Thank you so much for your reply.

Understood.