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Thread: Maths Week NZ

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    knocka's Avatar
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    Default Maths Week NZ

    This week is Maths Week in New Zealand and there is, of course, an extra focus on mathematical activities. This is one problem which was distributed at work.

    WEIGHTY BAGS

    Five bags were found, but for some unknown reason they could only be weighed in twos or threes.
    Bags A and B together wieghed 12 kg.
    Bags B and C together weighed 13.5 kg.
    Bags C and D together weighed 11.5 kg.
    Bags D and E together wieghed 8 kg.

    What was the weight of each bag?

    PM me with the answer. Twollars proportional to the weight of each bag will be given to the first five correct solutions.

    Bonus Twollars will be given to an explanation of how the solution was reached. The explanation has to be one that I can understand and one which I think others could understand when it is poste.

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    Before I start trying to figure this one out, don't we need to know the total weight of all the bags together?

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    Ooops.

    I left out one piece of information.

    Bags A, C and E together weighed 16 kg.

    Thanks, gabi.

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    Default Weighty Bags

    As well as pointing out that some information was missing from the puzzle as originally posted, gabi has solved this puzzle and provided an explanation I can understand.

    Now I'll just wait for some more weights, but I won't be undergoing any torment while I do so.


    Quote Originally Posted by knocka View Post
    WEIGHTY BAGS

    Five bags were found, but for some unknown reason they could only be weighed in twos or threes.
    Bags A and B together wieghed 12 kg.
    Bags B and C together weighed 13.5 kg.
    Bags C and D together weighed 11.5 kg.
    Bags D and E together wieghed 8 kg.

    What was the weight of each bag?

    PM me with the answer. Twollars proportional to the weight of each bag will be given to the first five correct solutions.

    Bonus Twollars will be given to an explanation of how the solution was reached. The explanation has to be one that I can understand and one which I think others could understand when it is poste.
    Also needed is the fact that: Bags A, C and E together weighed 16 kg.

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    Other interesting things around in Maths Week.

    This one caught my imagination - it's a bit "spooky" which made me think of Torment. No puzzle involved directly, but it can be considered a bit of a puzzle to find out why it works.

    http://www.cyberglass.biz/flshstuff/mindreader.php

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    I am using spoilers for anyone who doesn't want to know how that mind reader works:


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    The weighty bags have been weighed correctly three times. I'll just wait until tomorrow before posting the wieghts.

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    WEIGHTY BAGS

    A weighed 5.5 kg
    B weighed 6.5 kg
    C weighed 7 kg
    D weighed 4.5 kg
    E weighed 3.5 kg

    70 Twollars for gabi
    65 Twollars for sslug
    55 Twollars for corgipower
    45 Twollars for (knocka) he he
    35 Twollars for (knocka) he he

    Congratulations gabi, sslug and corgipower.
    May you enjoy your Torment.

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    Quote Originally Posted by knocka View Post
    Congratulations gabi, sslug and corgipower.
    May you enjoy your Torment.
    LOL thanks!!

    my torment right now are parts 2 and 3 of veni, vidi, vici and Moscow's puzzle.
    The other torment stopped for me at the first painting (that would be puzzle 5 or 6).

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    Default Explanation of Weighty Bags

    Bonus Twollars will be given to an explanation of how the solution was reached. The explanation has to be one that I can understand and one which I think others could understand when it is posted.
    50 Twollars for gabi whose explanation is posted below.
    Remember it is Maths Week and the explanation involves Mathematics.

    An alternative method for those who do not follow algebra so easily is the good old "guess and check" method. Guess a weight for B. Find the weights for the others and check to see whether A, C and E together weigh 16 kg. If they don't, have another guess for B and repeat the process. It does not take too long to find the correct answers.

    OK, I will try to make this explanation easy:

    A+B = 12; which means that A= 12-B

    Then I take
    C+D=11.5
    D+E+8

    and substract the second one from the first one which gives:

    C-E=3.5 so that means that E=C-3.5

    From A+C+E =16 I replace A and E to get:

    (12-B)+C+(C-3.5)=16

    I also know that B+C=13.5 so that B=13.5-C

    so:
    12 - (13.5 -C) +C+C-3.5=16

    which is :

    12 -13.5 +C+C+C-3.5=16

    3C= 16+3.5+1.5-12

    so C=21/3=7

    C=7
    B=13.5-7=6.5
    A=12-6.5=5.5
    E=C-3.5=7-3.5=3.5
    D=8-E=8-3.5=4.5

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