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Syllogism Questions [Doubt Cleareance thread]

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Comments

  • statements : 1. some cats are elephants
    2. No elephant is river
    3. All rivers are roads

    Conclusions :
    i) no cat is river
    ii) Some roads are rivers
    iii) some elephants are cats
    Iv) Some cats are rivers

    a) only i and ii follow
    b) only ii , iii , iv follow
    c) only either i or iv and iii follow
    d) Only i ii and iii
    e) None of these
  • e) None follow.

    ii and iii definitely follow, and either i or iv follow.
  • option E 2 and 3 are definitely true and either 1 or 4 is true(they both can't be true and if 1 is true then 4 is false and vice versa).
  • agree with woodpecker & stardust .. (e) is the answer

    @DareDevil

    even i had a doubt in that, whether to treat statement 1 as exclusive or to use with statement 3
    as we have to use all the statements , i chose the latter and it clearly says if the pin nails the light bulb
    sprinkles

    i think the ques is wrong or something cause in statement 1 it provides only 1 condition of light bulb sprinkling ad in the 3rd statement itself it provides another condition
  • e) None follow.

    ii and iii definitely follow, and either i or iv follow.
    I have a doubt here

    Does iii follow in every case?

    "Some cats are elephants" is not the same as " some elephants are cats"

    Please have a look at the attached image



  • @gdogra In the second case, some cats are elephants and all elephants are cats. But when all elephants are cats, then some elephants will also be cats. Hence (iii) will follow in every case.

    The question has only mentioned that some elephants are cats, it doesn't require some elephants to not be cats, therefore it is possible that all elephants can be cats, as is shown in your diagram. When 'all of A is B' is true, then 'some of A is B' is also true.
  • @Stardust1901 @Woodpecker thanks.. the book said d) but (I) alone couldn't have been possible.
    Have you guys looked at mrunals up-un method for these questions; I do them by Venn diagrams and general deductions/... is his method helpful/ better?
  • @Mags_Tell Many answers, even in the "reputable" books are wrong for CSAT questions, and that can get very confusing. There are no right or wrong methods as such, just do what you feels is faster. Compare your speeds with different methods if you feel a need to.
    I presonally don't use any particular methods, I just do what comes naturally with simple logic. Practice a lot of questions of every type, because that is the only way to gain proficiency and confidence.
  • @Mags_Tell

    Yeah, I've looked up Mrunal's up-un method. I found it really cumbersome and unwieldy. Mrunal's method requires a lot of memorization and there are chances one might mess up under exam pressure. I myself follow Venn diagram method which, in my opinion, is the easiest and most efficient.
  • Hi,
    Having a problem with these type of question,
    What will be your answer for below mentioned question

    Question : Examine the following statements regarding a set of balls:

    1. All balls are black.
    2. All balls are white.
    3. Only some balls are black.
    4. No balls are black.

    Assuming that balls can only be black or white, which two of the statement given above can both be true, but cannot both be false?
    Options:

    a) 1 and 4
    b) 1 and 3
    c) 2 and 3
    d) 2 and 4

    :(
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