1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Different logic

  1. Jun 8, 2014 #1

    adjacent

    User Avatar
    Gold Member

    1. The problem statement, all variables and given/known data
    ##\frac{1}{2}(5)=3## , based on this logic, what is ##\frac{1}{3}(10)##?

    3. The attempt at a solution
    In real life, ##\frac{1}{2}(5)=2.5## so
    2.5 --> 3
    Just like that, ##\frac{1}{3}(10)=\frac{10}{3}##
    so
    2.5 --> 3
    10/3 -->x

    Cross multiply---
    x=4
    I am not very sure whether this is correct or not. I don't know what logic this question assumes. Proportion or addition?
     
  2. jcsd
  3. Jun 8, 2014 #2

    micromass

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2016 Award

    You haven't described a logic yet. You have to state all the rules you are using. Just by stating that ##5/2=3## doesn't get you anywhere, because the only thing it implies is that ##5/2=3##, nothing else.
     
  4. Jun 8, 2014 #3

    adjacent

    User Avatar
    Gold Member

    I don't understand :confused:
     
  5. Jun 8, 2014 #4

    micromass

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2016 Award

    Can you list all the rules (axioms) of your system?
     
  6. Jun 8, 2014 #5

    adjacent

    User Avatar
    Gold Member

    Are you asking what I assumed?
    We know that(From the question) ##\frac{5}{2}=3=2.5## So what I assumed is
    ##3=k2.5## | ##k=1.2##
    Let ##i## be the false(Logic of the question) value and ##r## be the true value
    Then ##i=1.2r##
    So ##x=1.2 \times \frac{10}{3}##
    ##x=4##
     
  7. Jun 8, 2014 #6

    CAF123

    User Avatar
    Gold Member

    5/2 = 3 is simply a statement - there is nothing you can extrapolate from this to answer your question. The real number system obeys a set of axioms, so similarly there must exist a set of axioms that your system has to adhere to. Was there more given in the question or in an earlier exercise perhaps?
     
  8. Jun 8, 2014 #7

    adjacent

    User Avatar
    Gold Member

    That is the problem. I wrote exactly as the question was written. This is not an exercise, I saw this from the internet.

    So the question cannot be answered without knowing what rules it obeys();?
     
  9. Jun 8, 2014 #8

    micromass

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2016 Award

    The question as you asked in your OP cannot be answered. You need more information (such as other rules that the system obeys).
     
  10. Jun 8, 2014 #9

    adjacent

    User Avatar
    Gold Member

    Oh, I get it now. I see questions like these all over the internet. They normally use proportion.
    Anyway,thanks
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Different logic
  1. A Logic Problem (Replies: 2)

  2. Propositional logic (Replies: 1)

  3. Logic: Proofs (Replies: 3)

  4. Logic Terminology (Replies: 1)

  5. Logic question (Replies: 6)

Loading...