On Friday I posted this puzzle…..

Imagine a mythical family in which each daughter has the same number of brothers as she has sisters. In addition, each son has twice as many sisters as he has brothers. How many sons and daughters are there in this mythical family..?

If you have not tried to solve it, have a go now.  For everyone else, the answer is after the break.

The mythical family has four daughters and three sons.  Did you solve it?

I have produced an ebook containing 101 of the previous Friday Puzzles! It is called PUZZLED and is available for the Kindle (UK here and USA here) and on the iBookstore (UK here in the USA here). You can try 101 of the puzzles for free here.


    1. Mathematically, it might be argued that 0 children is a good answer. The problem is that it causes the question to make no sense. It makes it read like this: “there are no children. One of the girls has twice as many….” It’s like saying “there are no dragons. What color are the dragons?”

      As for the answer being 1. Well, um, no. 🙂

  1. The concerns I raised on Friday have not been addressed leading to an answer that old works for a real family with integral numbers of children with determinate genders and relationships,

    A true answer that works for a MYTHICAL family would at once be more satisfactory and more accurate.

    Using fizzy logic on comp;ex numbers leads to a range of solutions. As does pondering gender reassignments between the two statements and so on.

    A limited puzzle answer leads to limited understanding of the world. We should use these opportunities to explore the wonders of the universe around us rather than settling for a quick and so called obvious answers.

    As the stars are infinite above us so our understanding can be infinite within us. I believe that and so will never settle for the easy solution. Please join me in this quest.

    1. Matilda and MathMiles, most of the fun of richard’s puzzles comes from the monday morning pedantry.

      as BG noted on friday and today, “mythical” does not mean “hypothetical” and requires us to reject some common assumptions.

    2. @CTJ just because BG’s statement doesn’t mean ‘A’ – doesn’t mean it means ‘B’
      He’s aloud to talk utter nonsensical jibber, but I cannot jovially request his silence, without your input?
      I get that he’s making a poetic and humourous attempt to prove the non existence of evidential proof, but meanwhile, and more importantly, he just sounds like a fool. The stars are not infinite, and the size of the universe has no bearing on the way we interpret simple mathematic equations.
      He may feel that the world is infinite and that’s his way of justifying his search for the the truth, but for me, to say the universe is infinite is merely a defeatist way to view the universe. In his world, he cannot see past our solar system, in mine, it’s just the beginning.

    3. Thank you for your support @ctj.

      It is true that if the question was “can an unprotected person survive in space?” the answer (with a few caveats about survival time) would be “no”. But “can a mythical person survive in space?” has far wider answers. Clearly Superman and Yhwh can as can perhaps others like Tinman and Dr X. But Batman and Spiderman perhaps could not.

      To post a puzzle about mythical people and only allow an answer that pertains to mundane people is to miss a chance to education people on their limitless facility of imagination.

      To respond to @Matilda again. You may have missed the recent discovery of quantum gravity waves from the big bang cosmic echo that shows that our observable universe is only an immeasurable fraction of a vast infinite multiverse.

      But even without that anyone who has studied astrology with their heart knows that the influence of the stars on us is unbounded and so our influence on the universe (and universes) must also be unbounded. This is a simple application of Newton’s second law of action and reaction.

  2. Kinda like what I tell folks that ask: Each brothers has as many brothers as sisters, but each sister has three times as many brothers as sisters. How many boys and girls are there? I haven’t even reread the puzzle, I hope it isn’t the same question.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s