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If A, then B. If B, then C. If C, then D. If all of the [#permalink]
26 Sep 2009, 01:13

1

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A

B

C

D

E

Difficulty:

5% (low)

Question Stats:

38% (01:39) correct
63% (00:29) wrong based on 26 sessions

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.

Please help in takling such questions ,i ll appreciate detail explanation.

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.

Please help in takling such questions ,i ll appreciate detail explanation.

B.

We dont have a statement like D->A, so option A is out. option D is out as well, since there's no "E". Option E is not true, since it may be C then D. D is flawed as well, since it can be not D, but can be A. But if not B, then no C, since B-> C.

So option B is correct. Hope this helps. _________________

hi sacmanitin... ans is C.. first u have to understand what 'if A, then B.' means... anything which is A has to be B i.e. A is subset of B.... possible choices are.. i) 'if not A, then not B... need not be true as it could be something not part of both.. ii)'if B, then A.....need not be true as it could be something in B-A... various other choices ..only true choice is if not B, then not A... if it is not a part of B , itcannot be in A... putting this rule in ans only C remains...

thanks chetan , i now able to attack such problems ,from your reasoning ,i drew a diagram all the conditions can be represent like [d [c [b [a] ] ] ]

now from question stem

(A) If D, then A. ( it can be anything from d ,c ,b and a so eliminate) (B) If not B, then not C. (if not be then it can be c or not c ,eliminate) (C) If not D, then not A. (if not d then it is outside the biggest box so surely out of smallest box i e a ,correct) (D) If D, then E. (no information ,eliminate) (E) If not A, then not D. (it not in the smallest box ie not a ,it can be anything from b,c,d or not d ,so eliminate this choice as well)

(D) is totally wrong (A) is wrong because of reverse (B) is wrong. The premise did not mention If not B, then not C. Very clearly (E) is wrong, not A but appearance of C will make D true

POE, I got (C)

My another explanation: Imagine that A belong to B, B belong to C, and C belongs to D. You draw the circle around it like (D(C(B(A)))), you will eliminate all except for answer choice (C) _________________