If A, then B.
If B, then C.
If C, then D.
If all of the statements above are true, which of the following must also be true?
A. If D, then A
B. If not B, then not C
C. If not D, then not A
D. If D, then E
E. If not A, then not D
If A, then B. If B, then C....
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I would like to think of all the three statements independent and represent below:figs wrote:If A, then B.
If B, then C.
If C, then D.
If all of the statements above are true, which of the following must also be true?
A. If D, then A
B. If not B, then not C
C. If not D, then not A
D. If D, then E
E. If not A, then not D
A->B
B->C
C->D
A) It cannot be true.
C) It cannot be true.
D) Out of scope.
E) It cannot be true.
B) If not B then not C is true.
The answer is B.
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My answer: None of the above.figs wrote:If A, then B.
If B, then C.
If C, then D.
If all of the statements above are true, which of the following must also be true?
A. If D, then A
B. If not B, then not C
C. If not D, then not A
D. If D, then E
E. If not A, then not D
B sounds like a plausible choice at first, but not B doesn't necessarily imply not C.
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Figs can you post the OA pls?figs wrote:If A, then B.
If B, then C.
If C, then D.
If all of the statements above are true, which of the following must also be true?
A. If D, then A
B. If not B, then not C
C. If not D, then not A
D. If D, then E
E. If not A, then not D
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The OA is CKICKGMATASS123 wrote:Figs can you post the OA pls?figs wrote:If A, then B.
If B, then C.
If C, then D.
If all of the statements above are true, which of the following must also be true?
A. If D, then A
B. If not B, then not C
C. If not D, then not A
D. If D, then E
E. If not A, then not D
This is a logic problem and we shouldn't be expecting this as part of the GMAT. I am going to show how we can get it from truth table.
(-> is then) From the given information, we can conclude that A->D is true. I will construct the truth table using https://en.wikipedia.org/wiki/Truth_tabl ... mplication
T= TRUE
F=FALSE
Please look at the file attached.
A->D and ~D->~A have the same truth table and hence is the right answer.
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Another (slightly simplified) way of seeing this is as follows:
A implies B
B implies C
C implies D
all together imply that A implies D. By the contrapositive (not converse!), we have that not D implies not A. Generally, for ALL statements, if A implies B, then "not B" implies " not A".
For example, if you're a human, you have a brain. If you don't have a brain, you're not a human.
A implies B
B implies C
C implies D
all together imply that A implies D. By the contrapositive (not converse!), we have that not D implies not A. Generally, for ALL statements, if A implies B, then "not B" implies " not A".
For example, if you're a human, you have a brain. If you don't have a brain, you're not a human.
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