Tuesday, 16 February 2016

Find The Weight

17 comments:

  1. simple quadratic equation. Bunny = 4Kg, Cat = 6Kg, Dog = 18 Kg

    Answer is 28Kg

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    Replies
    1. If bunny was 4 and dog was 18 then bunny plus dog would be 22, not 20. They were each weighed twice, add up each weighing and divide by two and the total is 27. It doesn't matter what each weighs separately.

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  2. I'd rather figure out how all the animals are able to read the scale when there are two of them on it but not when there are three. And I would LOVE to know how they are able to speak!

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  3. It's 27 kg. If we sum up the first three pictures, we get 54 kg, and that would have two bunnies, two cats, and two dogs. Divide by two and you get their combined 27 kg.

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  4. (bunny + cat) + (bunny + dog) + (cat + dog) = 10 + 20 + 24, add everything
    2bunny + 2cat + 2dog = 54, divide by 2
    bunny + cat + dog = 27

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  5. r+c=10
    r+d=20
    c+d=24

    2r+c+d=30
    c+d=24
    (subtract the bottom line from the top)
    2r=8
    r=4

    plug r=4 into the top equations to get
    c=6
    d=18

    All together:
    c+r+d = 28

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    Replies
    1. On line 7 you made the mistake of 30 - 24 = 8 when it should be 6.
      This then in turns gives you;
      r = 4 instead of 3,
      c = 6 instead of 7,
      d = 18 instead of 17, and
      r+c+d = 28 instead of 27.

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    2. Argh, sorry, typo. That's what you get for doing mental arithmetic in bed.

      2r+c+d=30
      c+d=24
      (subtract the bottom line from the top)
      2r=6
      r=3

      plug r=3 into the top equations to get
      c = 7
      d = 17

      All together:
      c+r+d = 27

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    3. 'cept for the bit where 2r should be 6 when you did your subtraction. (30-24 = 6)

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  6. Bunny 3kg cat 7kg dog 17 kg equals 27kg

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  7. Answer: 27 Kg

    (1) R + C = 10;
    (2) R + D = 20;
    (3) C + D = 24;
    (4) R + C + D = ?

    (5) From equations (1) and (2) we can subtract R to tell us that the difference between C and D must be 10.

    (6) From equations (2) and (3) we can subtract D to tell us that the difference between R and C must be 4.

    (7) Since we know that R + C = 10, we can substitute our deduction from (6), R + (R + 4) = 10, 2R + 4 = 10, R = 3

    (8) Since we now know R, we can substitute it any either of the other equations to get the values of C and D;
    (1); 3 + C = 10, C = 7
    (2); 3 + D = 20, D = 17;

    Therefore: (4): R + C + D = 3 + 7 + 17 = 27.

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  8. An no Rachel, it's not a quadractic equation, there are no exponents involved whatsoever.

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  9. You lot are so smart! Hey wait...did someone say TALKING ANIMALS??? ;)

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  10. The scale is broken. The arrow doesn't move for the first three weighings, then when they all get on, it displays a question mark.

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