JNU 2012 LOGIC QUESTION

[vandita24x7]

Q) THREE TRUCKS A,B,C are used for transporting wheat and rice. The
following information is given

a) If A carried wheat, then B carried rice

b) If A carried rice, then C carried wheat

c) If B carried wheat, then C carried rice

Which truck always carried the same thing?

a) A        b) B        c) C

HOW TO SOLVE SUCH A PROBLEM??

[Masterpiece]

CONTENTS DELETED

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[vandita24x7]

no but the correct answer is B...... pls Amit Sir help!

[Nag27]

OK here's my logic to the answer:

When A carries wheat, B carries rice as per condition (a). It isn't defined what C carried in such a situation (since neither is A carrying rice not has B carried wheat).

When A carries rice, C carried wheat as per condition (b). Now, for B to carry wheat, C should have been carrying rice as per condition (c). But it is carrying wheat, hence B did not carry wheat, and the only other option was for it to carry rice.

So B carries only rice in all scenarios.

[vandita24x7]

Nag27 I still don't follow ur explanation... pls help!

[arsh]

Hi

there are 2*2*2 possible cases. as each a,b and c can carry w(wheat) or r(rice).
we have to find all the plausible cases and from them determine which truck was carrying the same thing.
NOTE:"if a carried wheat then b carries rice" implies that c can carry wheat or rice.
let xxx be what a,b and c are carrying espectively
1.www cant be as when a is w, b is carrying r
2.rrr not poss since wen a is r then c is w
3. wwr not poss since wen a is w, b is r
4.rwr   POSSIBLE
5.rww  not poss since wen b is w then c is r
6.wrw POSSIBLE
7.wrr POSSIBLE
8.rrw POSSIBLE

so truck b is always carrying rice.

[Sinistral]

i think 4th (rwr) is also not possible. because if A is carrying rice => C should carry wheat

[arsh]

Thats correct. my bad :)

[maahi]

please help me with d following questions 1,27,33,34,35,36

[maahi]

more problems : 62  63  78 79 93 94  91  

[Nitschk22]

Transporting grains need a perfect and quantity check as well. Hired one of the famous logistics services Dallas to export some jewels to the client. Was first worried about the safety but my business partner was quite sure about their honest and loyal classifications. Will definitely avail their services for all of my orders from now.

[deepshika1]

arsh wrote

Hi

there are 2*2*2 possible cases. as each a,b and c can carry w(wheat) or r(rice).
we have to find all the plausible cases and from them determine which truck was carrying the same thing.
NOTE:"if a carried wheat then b carries rice" implies that c can carry wheat or rice.
let xxx be what a,b and c are carrying espectively
1.www cant be as when a is w, b is carrying r
2.rrr not poss since wen a is r then c is w
3. wwr not poss since wen a is w, b is r
4.rwr   POSSIBLE
5.rww  not poss since wen b is w then c is r
6.wrw POSSIBLE
7.wrr POSSIBLE
8.rrw POSSIBLE

so truck b is always carrying rice.

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Ohh this is actually brilliant. Checking the combinations is something I did not think of.
I have been seeing a lot of these question in UPSC general knowledge section. Could you please tell me a few more hacks like these so that it can help me in the exam?
Where did you learn this method from?
Did you attend a coaching class?
Please let me know!