Math is FUN!

Well, actually, I’m in book 6B, but for some reason that one wasn’t available through Amazon.  Anyway, yes, I’ve been doing math for fun.  Much to my children’s puzzlement and disbelief.

This problem is a cool one, just requiring a little logic to think it through.

Harry gave Tom and Dick as many marbles as each already had.  Then Dick gave Tom and Harry as many marbles as each then had.  Finally, Tom gave Dick and Harry as many marbles as each then had.  The 3 boys ended up with 8 marbles each.  How many marbles did each boy have at first? 

Love that convoluted process–why didn’t they just throw them all together and then divvy them up equally, anyway?  Oh, yeah, because it’s so fun to figure it out! 

Now this one has me stumped so far!  See if you can figure it out.

5 roosters, 2 hens, and 2 chicks weigh 15.7 kg.  3 roosters and 3 hens weigh 12 kg.  Each chick weighs 0.4 kg.  If each hen weighs the same and each rooster weighs the same, what is the total weight of 5 roosters and 2 chicks? 

Huh?    Say what?  I guess when they say Intensive in Singapore, they mean Intensive!  Sometimes the biggest challenge for me is to figure out a way to do it without algebra.  With this one, though, I’m not even coming up with an algebraic way.  Oh, well, it’s late.  Maybe another day.  I’m not looking at the answer.  Yet.

I bought this book for my 12 year old son, who is now working in Singapore level 6B, but after working through some of it myself, I’m seriously wondering whether to give it to him.  We may just go on to algebra–it might be easier!


About dayuntoday

I'm a wonderer. I spend a lot of time mulling, pondering, and cogitating. This is just a place to park some of those thoughts.
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12 Responses to Math is FUN!

  1. Anonymous says:

    Roosters weigh 2.3 KG each
    Hens weigh 1.7 KG each
    The weight of the chickens is known.
    How to solve:
    X = Roosters, Y = Hens
    5x + 2y +.8 = 15.7
    3x + 3y = 12
    Simply solve for x or y and subsitute in the other equation.   It becomes a simple matter to solve for x and y at that point.

  2. fwren says:

    I do NOT want to think this hard anymore about MATH!  !!!

  3. Anonymous says:

    My kids never see the point to those kinds of problems, and I have to agree with them.  I mean honestly, I would simply get a scale and weigh each chicken individually if I were in the situation where I’m about to mail live chickens somewhere.  And who cares how many marbles each boy had at first as long as they are playing quietly and not causing a ruckus?  Oh well, at least your math books aren’t asking you what color addition would be or what sound subtraction would make!

  4. I like logic puzzles, too.  But, I’m glad someone else tackled this one. I’ve got to go do Saxon 76 with my kids and would have spent time finding chicken weights instead. We leave in seven days for England!

  5. BooksForMe says:

    It becomes a simple matter to solve for x and y at that point.  Well, yeah,  BUT, where do you go from there?  I got that far myself, but then I just couldn’t get any further.  I do enjoy math and see as a puzzle, but I think I’m only willing to take the “game” so far.  LOLWill we ever know the answer?

  6. Anonymous says:

    BooksforMe:  The answers are listed in my comment.  Solve one equation for x.  Plug that value in the other equation and solve for y.  You will then get the x and y values.

  7. homefire says:

    Well, I finally did figure it out this morning, and I even figured out a way to do it without algebra (which they haven’t taught yet) but it certainly seemed cumbersome.  Algebra is definitely easier, and I’m not sure why they give them problems like this before they learn algebra. 
    Maybe it helps their brains to actually understand what they’re doing when they start algebra?  Because I have met many people (and I used to be one of them!) who can go through the motions of algebra, but have not a clue why they’re doing it.
    If anyone really wants to know how to do it without algebra, ask.  Otherwise, I’m not going into it!  Because I know most of you couldn’t care less!     

  8. homefire says:

    Oh, and the answer, BFM, is 12.3 kg.  5 roosters at 2.3 each, and 2 chicks at .4 each.  11.5 + 0.8 = 12.3
    I did another three pages of these problems today and got into some real doozies with ratios.  One I only got by trial and error.  Anybody game for that one? 

  9. BooksForMe says:

    Yes, I do want to know how you solved it without Algebra, if you are inspired to post the solution.

  10. homefire says:

    BFM, it involved making a sort of graph and then rearranging the elements of it, which they do teach them to do in Singapore Math.  I’ll try to give my version–hopefully I’ll be able to remember how I did it!
    |rst|rst|rst|rst|rst|hen|hen|chick|chick| = 15.7,
         and the weight of the chicks is known as .4 each, so
    |rst|rst|rst|rst|rst|hen|hen| = 14.9
         The other given info is
    |rst|rst|rst|hen|hen|hen| = 12
         Match those graphs up and you have
    |rst|rst|rst|rst|rst|hen|hen|          =14.9             |rst|rst|rst|hen|hen|hen|    =12
        From that, you can see that
    two roosters – 2.9 = a hen
        So when you plug that in to the first equation, you have this:
    |rst|rst|rst|rst|rst|—–hen—–|—–hen—–| = 14.9|rst|rst|rst|rst|rst|rst|rst| -2.9|rst|rst| -2.9| = 14.9
    That means that 9 roosters = 20.7, so one rooster weighs 2.3
    So five roosters would be 11.5, two chicks are 0.8, so the answer will be 12.3
    Hope you can decipher what I’m doing–the formatting leaves a lot to be desired.  And it seems pretty convoluted to me, but it does compute logically, and I think it may show kids what’s really happening in algebra better than the way I learned.  What do you think?

  11. BooksForMe says:

    Oooh…that’s very cool!

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