All etching tools are either pin-tipped or bladed. While some bladed

Hey , I don't get it.. Can you eliminate answer choice E ., how B could be the answer, considering
All Etching tools = ET = 100
Bladed et 70, Pink point et = 30 ,
Some bladed et can do engraving = 60 some don't = 10
Still et for engraving ( 60+ 30) are greater than not engraving et.

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Hey,happy to help.
Assumption is something which is not mentioned in the question. So far so good.
The question states that all P can be used for engraving. Some B also but some B cannot.
Now looking at option E, all tools that cannot be used for engraving must be B type. It's exactly what's mentioned in the question. Hence it cannot be an assumption n hence it's a wrong option.
Correct answer choice B.

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A Tree diagram would help in better visualization.

Etching Tools(Assume 100)--------- Pin Tipped (Say 40)------ Used for engraving (40)
------- Not engraving (0)

---------Bladed (Say 60)------------Used for engraving (1- assuming minimum value)
------------Not engraving (59)

Total no. of etching tools not used for engraving = 59
Total no. of tools used for engraving = 41

Conclusion: There are more etching tools that are used for engraving than there are etching tools that are not used for engraving.

In, our case the conclusion wont stand. So, for the conclusion to stand, rework the example

Etching Tools(Assume 100)--------- Pin Tipped (Say 50)------ Used for engraving (50)
------- Not engraving (0)

---------Bladed (Say 50)------------Used for engraving (1- assuming minimum value)
------------Not engraving (49)

Total no. of etching tools not used for engraving = 49
Total no. of tools used for engraving = 51

Therefore, in this case there are more etching tools that are used for engraving than there are etching tools that are not used for engraving.

So, the author assumed Pin tipped tools to be greater than or equal to Bladed tools.





All tools whether used for engraving or not engraving are essentially etching tools. No new information there.



This is according to assumption.



The argument says etching tools are either pin tipped or bladed. So, that means an etching tool cannot be both pin tipped and bladed. So, new information here.




Does'nt help with the conclusion if you take majority or just 1.



May be. May be not. But will not help us with the conclusion.

This question can be better solved by creating 2*2 matrix table, in which one side is Pin and Bladed and other side is Engrave and Non-Engrave. Now, put the data as it said in the argument and you will see how B is correct.

Hi, Could anyone please help regarding why the answer cannot be option C

Thanks in advance,
Anurag

If that was the case, then consider this:

Etching Tools(Assume 100)--------- Pin Tipped (Say 60)------ Used for engraving (60)
------- Not engraving (0)

---------Bladed (Say 40)------------Used for engraving (1- assuming minimum value)
------------Not engraving (39)

Total no. of etching tools not used for engraving = 39
Total no. of tools used for engraving = 61

(B) There are as many pin-tipped etching tools as there are bladed etching tools.

- Wait. This is not the truth based on the discussion above. So, There are more pin-tipped etching tools than bladed etching tools; so there are not as many PT etching tools as there are bladed etching tools because there are more PT. How could the conclusion holds true in this case then?

GMATNinja GMATNinjaTwo nightblade354
In the end I did choose the right option but could anyone of you as and when please provide the OE for this question.

Thank you.

All etching tools are either pin-tipped or bladed. While some bladed etching tools are used for engraving, some are not. On the other hand, all pin-tipped etching tools are used for engraving. Thus, there are more etching tools that are used for engraving than there are etching tools that are not used for engraving.

The conclusion of the argument follows logically if which one of the following is assumed?

(A) All tools used for engraving are etching tools as well.
(B) There are as many pin-tipped etching tools as there are bladed etching tools.
(C) No etching tool is both pin-tipped and bladed.
(D) The majority of bladed etching tools are not used for engraving.
(E) All etching tools that are not used for engraving are bladed.
can you plz help me how can we with this question
how can we apply negation rule in option B and c and how does option C is not the answer by using negation rule
THANK YOU

I received a PM requesting that I comment.

Premise:
While all pin-tipped etching tools are used for engraving, some bladed etching tools are NOT used for engraving.
Conclusion:
There are more etching tools used for engraving than there are etching tools not used for engraving.

To identify the assumption, apply the NEGATION TEST.
When the correct answer is negated, the conclusion will be invalidated.
Note:
Negation of as many X as Y = FEWER X THAN Y.

B, negated:
There are fewer pin-tipped etching tools than bladed etching tools.
Here -- since the majority of etching tools are bladed -- the number of bladed etching tools NOT used for engraving can be greater than the total number of etching tools that ARE used for engraving, invalidating the conclusion that there are more etching tools used for engraving than there are etching tools not used for engraving.
Since the negation of B invalidates the conclusion, B is an ASSUMPTION: a statement that MUST BE TRUE for the conclusion to hold.



C, negated:
Some etching tools are both pin-tipped and bladed.
This negation seems to contradict the PREMISE that all etching tools are either pin-tipped OR bladed.
A negation that attempts to affect a premise is invalid.
A valid negation must hurt the CONCLUSION.
Eliminate C.

I got why option C is not the answer but still facing difficulty with option B if we negate option B then it becomes There are fewer pin-tipped etching tools than bladed etching tools now there are two possibilities
1)The no of bladed tools NOT used for engraving are MORE then no of bladed tools used for engraving then our conclusion that there more etching tools that are used for engraving than there are etching tools that are NOT used for engraving shatters.
but if we consider second possibility that The no of bladed tools NOT used for engraving are LESS then no of bladed tools used for engraving then this possibility supports our conclusion then how can this option be our answer in which one possibility shatters while other supports our conclusion.and in question it is given that the ''some bladed etching tools are used for engraving, some are not'' this word ''some'' is quite vague so we have to consider both the possibilities one possibility in which the no of bladed tools NOT used for engraving are MORE then no of bladed tools used for engraving and other in which The no of bladed tools NOT used for engraving are LESS then no of bladed tools used for engraving
I really need your guidance
THANK YOU

The contrapositive of IF A, THEN B is IF NOT B, THEN NOT A.
If an IF-THEN statement is true, its contrapositive is also true.
True IF-THEN statement:
If John is in Times Square, then John is in New York.
Contrapositive:
If John is not in New York, then John is not in Times Square.



As noted in my earlier post:
If there are NOT as many pin-tipped etching tools as bladed etching tools. then it is possible that most etching tools are NOT used for engraving.
Contrapositive:
If the blue statement above is NOT possible -- in other words, if most etching tools ARE used for engraving -- then there ARE as many pin-tipped etching tools as bladed etching tools.
The THEN-portion of an IF-THEN statement is a NECESSARY CONDITION.
Thus, to conclude that most etching tools ARE used for engraving, it is NECESSARY that there are as many pin-tipped etching tools as bladed etching tools.
Implication:
The green statement above is an assumption: a statement that MUST BE TRUE for the conclusion to hold.

I think the issue that most people have is that when you “Negate” Answer Choice B, you can come up with Numbers where Blade > Pin and the conclusion still stands

This is because we don’t know the break down of “some” bladed- ETCHING Vs. “some” bladed-NOT Etch


However, put yourself in the author’s shoes. He’s looking at info. It shows that some bladed are used for etching, some are not.

But, ALL pin are used for etching.

He or she therefore makes the conclusion that overall there must be more etching than NON etching.

To be absolutely safe in his conclusion, what must the author be thinking in his head?

If you were the author making the conclusion and you were given the information/facts and then concluded “there is more etching > NON etching”, what would you have to think to be absolutely sure your conclusion is correct?

Most of us would realize it’s a fault argument, but this author would have to be thinking (to be absolutely “safe” that his conclusion is valid) that there are more Pin than > Blade.

Only in that case am I, the author, sure that there are more etching > NON etching.


I hope that helped somewhat. That was my thought process anyway.....

Also, I eliminated the other 4.

A just repeats the given facts in a new way. The other 3 aren’t correct.

By process of elimination, I would pick B

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Key to this question is that "some" means 1 or more. "Some" has been used in passage while describing the use of bladed etching tools. If you keep the above information in mind and then negate B, the conclusion would fall apart since pin-etched could be less than bladed, destroying the argument completely.

It was tough fight between B and E for me.
Though B certainly helps prove the conclusion, E does create a problem if one does not takes into account of etching tools not discussed.

Dear experts,
I have some doubts on this question.
Though I understand 100% why B can make the conclusion True. I believe if I negate B, the conclusion does not 100% collapse
negated B is: There are not as many pin-tipped etching tools as there are bladed etching tools.

So I have 1 example
etching
pin-tipped 1 1 engraving
bladed 99 97 engraving
2 not engraving

Then I related to the example in Powerscore CR
"For example, let us say that an argument requires the
assumption ???all dogs are intelligent.??? The correct answer could be that
statement, or even a subset statement such as ???all black dogs are intelligent???
or ???all large dogs are intelligent??? (black dogs and large dogs being subsets
of the overall group of dogs, of course). But, additional information would
rule out the answer, as in the following case: ???All dogs and cats are
intelligent.??? The additional information about cats is not part of the author???s
assumption, and would make the answer choice incorrect."

In the question and the example, the assumption both present "more conditions" necessary for the conclusion to be True.

This is why I am confused with this question. Please help

Note that this is a "sufficient assumption" question, not the regular "necessary assumption" question of GMAT.

The conclusion of the argument follows logically if which one of the following is assumed?

What will make the conclusion follow logically? (not what is necessary for the conclusion)

If some bladed tools are used for engraving and some are not while all pin tipped tools are used for engraving, when can we say that there are more tools used for engraving than not used for engraving?
If we know that there are as many pin tipped tools as bladed tools, then we know for sure that there are more tools for engraving.

If there are total 100 tools - pin tipped + bladed
When pin tipped are 50 and bladed are 50 and all pin tipped are used for engraving and some bladed are used for engraving then we can say logically that more tools are used for engraving than not used for engraving.
Do they need to be 50 - 50? No. But if they are, does the conclusion follow? Yes. This is what we are looking for.