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CR if A then B

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CR if A then B

by ansh.kumar » Thu Feb 12, 2009 8:50 am
7. 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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by bmlaud » Thu Feb 12, 2009 1:00 pm
IMO E
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by bravotalks » Thu Feb 12, 2009 5:40 pm
IMO C

The question doesn't say there are no ways to arrive at D other than
A -> B -> C -> D.
So, we cannot say E

But, if A happened then B happens, then C happens, and then D happens. So, if D didn't happen then A wouldn't have happened. In other words 'If not D, but A happens' is NOT possible. So (C).
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by hardik.jadeja » Fri Feb 13, 2009 3:46 pm
I'd go with C.
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by jeevan.Gk » Sat Feb 14, 2009 9:56 am
Easy pick.. Cause effect relation
It should be C undoubtedly
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by bmlaud » Sat Feb 14, 2009 10:47 am
I didn't get it. I look at the problem this way

If A doesn't happen, B will not happen
same way if not B then not C and then not D

so If not A then not D ??????

what 's the mistake?, but this way we end up with two correct answers B and E.
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by Karen » Sat Feb 14, 2009 11:33 am
BMlaud, you're looking at it backwards. It's C. As someone pointed out above, the problem doesn't say that A causing B causing C is the *only* way to get to D. It only says that if A happens, then B, C and D have to happen.

Translate it into real-world terms. "If it rains, the streets get wet." That means that if the streets are *not* wet, we can say that it hasn't been raining. But you can't say that if it doesn't rain, the streets won't get wet. Maybe the streets will get wet from people watering their lawns.

More parallel to this problem, suppose it's "If if rains, the streets get wet. If the streets get wet, car accidents happen. If car accidents happen, people get injured." So you can conclude from that that if no one is injured, it hasn't been raining. But you *can't* conclude from that that if it hasn't rained, no one has been injured. Other factors could cause injuries. Other factors could cause car accidents. And other factors could cause wet streets.
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by bmlaud » Sat Feb 14, 2009 11:55 pm
Thanks Karen,

The example that you have given makes it clear.
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by deep » Sun Feb 15, 2009 3:03 am
Principle of logical reasoning,
If A happen then B will happen.
Right Conclusion: If B doesn't happen then A doesn't happen.

Wrong Conclusion: If A doesn't happen then B doesn't happen.

Reason being A produce B this doesn't not mean that A is the only source through which B is happening it can happen due to C too. But if B is not there then surely A is not there.

If you apply this concept answer is C.
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by 4meonly » Sun Feb 15, 2009 3:21 am
You can solve this question through sets - let them be A, B, C, D.

А)----B)-----C)-----D)
A is the part of B, B is the part of C, C - part of D. Obviuosly, A is the part of D.

Answers
(A) If D, then A.
Variants
А)----B)-----C)--*---D)
А)----B)--*---C)-----D)
А)--*--B)-----C)-----D)
if * is the part of D, it doesnot guarantee that * belongs to A.
INCORRECT

The same with other answers
(B) If not B, then not C.
А)----B)--*---C)-----D)
А)----B)-----C)--*---D)
INCORRECT

(C) If not D, then not A.
А)----B)-----C)-----D) *
CORRECT

(D) If D, then E.
INCORRECT

(E) If not A, then not D.
INCORRECT


С
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by srichinni28 » Tue Nov 05, 2013 11:08 am
Ans C
causal logic.
if a --> b then if not b means not a.
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