If Martin introduces an amendment to Evans’s bill, then Johnson and Ll

Question

If Martin introduces an amendment to Evans’s bill, then Johnson and Lloyd will both vote the same way. If Evans speaks against Lloyd’s position, Johnson will defend anyone voting with him. Martin will introduce an amendment to Evans’s bill only if Evans speaks against Johnson’s position.

If the above statements are true, each of the following can be true  EXCEPT

(A) if Evans speaks against Johnson’s position, Lloyd will not vote with Johnson.

(B) if Martin introduces an amendment to Evans’s bill, then Evans has spoken against Johnson’s position.

(C) if Evans speaks against Johnson’s position, Martin will not introduce an amendment to Evans’ bill.

(D) if Martin introduces an amendment to Evans’s bill, then either Johnson will not vote with Lloyd or Evans did not speak against Johnson’s position.

(E) if either Evans did not speak against Lloyd’s position or Martin did not introduce an amendment to Evans’s bill, then either Johnson did not defend Lloyd or Martin spoke against Johnson’s position.

Source:  Master GMAT

hellosanthosh2k2 · Accepted Answer

very tricky

Answer (D)

tempting to choose C, but C can be true also.

Martin will introduce an amendment to Evans’s bill only if Evans speaks against Johnson’s position

A, only if B => if A, then it must be B definitely. => If Martin introduces an amendment to Evans’s bill(A) -> then definitely Evans has spoken against Johnson’s position(B)
 but if B, -> may or may not be A.

So option C can be true as well.

On other hand D.

If Martin introduces an amendment to Evans’s bill (A), -> Johnson and Lloyd will both vote the same way (C)
from above, If Martin introduces an amendment to Evans’s bill(A) -> then definitely Evans has spoken against Johnson’s position(B)

in other words, If Martin introduces an amendment to Evans’s bill (A) -> Johnson and Lloyd will both vote the same way (C)  AND  definitely Evans has spoken against Johnson’s position(B)

A -> B  AND  C

option D says 
if Martin introduces an amendment to Evans’s bill, -> either Johnson will not vote with Lloyd or Evans did not speak against Johnson’s position

it is of form A -> (not B)  OR  (not C) which is definitely false, as we know from above A -> B  AND  C

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Mahmud6 · Answer

Very tough question. Not sure whether it is GMAT like question.

(A) if Evans speaks against Johnson’s position, Lloyd will not vote with Johnson.

The argument says if Martin introduces an amendment to Evans’s bill, then Johnson and Lloyd will both vote the same way. This implies that we can't say whether Johnson and Lloyd will both vote the same way if Martin doesn't introduce an amendment to Evans’s bill.
The argument again says Martin will introduce an amendment to Evans’s bill only if Evans speaks against Johnson’s position.
So, if Martin introduces an amendment to Evans’s bill, Evans MUST speaks against Johnson’s position. But this is NOT ALWAYS TRUE that if Evans speaks against Johnson’s position, Martin will introduce an amendment to Evans’s bill. So, we are not sure whether Martin will introduce an amendment to Evans’s bill. Hence, we are not certain whether Lloyd will or will not vote with Johnson. So, it may or may not be true.

(B) if Martin introduces an amendment to Evans’s bill, then Evans has spoken against Johnson’s position.
 
True. It is clearly paraphrased from argument.

(C) if Evans speaks against Johnson’s position, Martin will not introduce an amendment to Evans’ bill.
 
May be true.

Let's consider the following:

Y will happen only if X happens => If X happens Y may or may not happen.

The argument says Martin will introduce an amendment to Evans’s bill only if Evans speaks against Johnson’s position.
Y=Martin will introduce an amendment to Evans’s bill 
X=Evans speaks against Johnson’s position

So, if Evans speaks against Johnson’s position, Martin may or may not introduce an amendment to Evans’ bill.

(D) if Martin introduces an amendment to Evans’s bill, then either Johnson will not vote with Lloyd or Evans did not speak against Johnson’s position.

There are two issues here,
 a. If Martin introduces an amendment to Evans’s bill, then Johnson will not vote with Lloyd
 The argument clearly says that if Martin introduces an amendment to Evans’s bill, then Johnson and Lloyd will both vote the same way. So, the above statement is NOT True.

b. If Martin introduces an amendment to Evans’s bill, then Evans did not speak against Johnson’s position
 The statement says Martin will introduce an amendment to Evans’s bill  only if  Evans speaks against Johnson’s position. Therefore, it can not be happened that Martin introduces an amendment to Evans’s bill but Evans did not speak against Johnson’s position. So, it is NOT True.

(E) if either Evans did not speak against Lloyd’s position or Martin did not introduce an amendment to Evans’s bill, then either Johnson did not defend Lloyd or Martin spoke against Johnson’s position.

There are also two issues here,
 a. If Evans did not speak against Lloyd’s position, then Johnson did not defend Lloyd.
 The argument tells us that if Evans speaks against Lloyd’s position, Johnson will defend anyone voting with him. So, it can be true that if Evans did not speak against Lloyd’s position, then Johnson did not defend Lloyd.

b. If Martin did not introduce an amendment to Evans’s bill, then Martin spoke against Johnson’s position.
 The argument says Martin will introduce an amendment to Evans’s bill only if Evans speaks against Johnson’s position. From this statement we are not certain if Martin did not introduce an amendment to Evans’s bill, whether Martin spoke against Johnson’s position. So it may be true.

D is the correct answer.

Aadhitthyaa · Answer

I dont think this is a GMAT question. More like a question which you have to just guess and move on, rather than breaking your head.

Sajjad1994 · Answer

Official Explanation

Let us use letters to represent the form of the argument. The first sentence is our old friend:  “If P, then Q.”

Now we must be careful not to use the same letter to stand for a different statement. No part of the second sentence is also a part of the first one, so we must use a new set of letters:  “If R, then S.”  Do not be confused by the internal structure of the sentences. Though the second clause of the first sentence speaks about Johnson and Lloyd voting the same way, the second clause of the second sentence speaks about Johnson’s defending someone. So the two statements are different ideas and require different letters. The first clause of the third sentence is the same idea as the first clause of the first sentence, so we use letter P again, but the second clause is different, T. The third sentence uses the phrase  “only if,” “P only if T,”  which can also be written:  “If P, then T.”

The correct answer is (D).

If Martin introduces an amendment to Evans’s bill, then Johnson and Ll

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