First, on Monday I am giving a public talk at the University of Hertfordshire about the paranormal on film….and it is free!  Hope you can make it – details here.  OK, to the puzzle…..

I have decided to hold a Mouse Clicking Competition.  So far, there are only three entrants – John, James and Jack.  John can click a mouse 10 times in 10 seconds. James can click a mouse 20 times in 20 seconds. Jack can click a mouse 5 times in 5 seconds. In my competition, the timing period begins with the first mouse click and ends with the final click. Which one of these entrants would be the first to complete 40 clicks?

As ever, please do NOT post your answers, but do say if you think you have solved the puzzle and how long it took. Solution on Monday.

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


    1. Jup… but it would also work with “automated click – machines”…

      Took me a few seconds to have the “most probable” solution under the most likely assumptions..

  1. I got it right after finishing reading… Mmmh, I guess I must be wrong because it was way too fast compared to every other puzzle I tried.

  2. It took about 10 secs, about the amount of time to read the puzzle. I wonder what people are doing who are taking minutes to solve. 🙂

    1. OK, I recant my previous post. After thinking more about what’s needed to generate a click, another answer (which I’m sure is the intended correct answer) makes more sense. It does, however, require an assumption that’s not explicitly given in the problem statement.

  3. I don’t always get the asnwer straight away (e.g. the Boston-NY train), but like Lehcyfer, I can’t see any puzzle or lateral thinking required for this one. So much so, I suspect there must be more to it and my answer is wrong.

  4. Took a few seconds to engage mind, a few more to arrive at an instinctive answer, and a few more to check the maths. Today, I’m officially good!

  5. Very easy, but how did John, James and Jack ever find out that they could only do that amount of clicks? And where was ‘forty-click’ Jerry when he was needed?

  6. I agree with serverdude – anyone solving this in under a second or two has DEFINITELY got the wrong answer. The right answer – when you find it – will show very definite first, second, and third places for the three clickers.

  7. Has anyone else noticed that John can click a mouse 5 times in 5 seconds too?
    Gosh – I’ve just noticed that James can as well…..
    I haven’t actually “solved” it as I’m not very good at semantics.

    1. Does that mean you are agreeing with my comment, disagreeing with it or sitting on one of these fence posts that
      people are talking about Martin?

    2. Help me here Sidney please. So you are saying that John (who can click a mouse 10 times in ten seconds) cannot click the mouse 5 times within 5 seconds?

  8. About 60 seconds of thinking spread out over a couple of minutes, in batches of 4*5s, 2*10s and 1 of 20s.

    Seriously, though, it was clear that the fastest person’s names begins with J

  9. Had an instinctive answer which popped into my head immediately on reading the question. Wasn’t sure why that was my instinct though, so I did the maths. It was right after all, so you could either say “immediately” or “5 minutes” as to how long it took.

  10. Took a while before I understood the question. (30 seconds) Slowly I understood what was going on (10 seconds) then I got the answer (5 seconds). So it took me less then a minute.

    By the way, I’d win from these three entrants easily.

    1. Martin to answer your question I need to know if the fence is linear or joined up and enclosing an area.

    2. They are wrong
      I’ll give you a hint though – there is only one “specific winner” and his initials are RW.

  11. I’m a little worried that some people are doing maths, simple division aside, it’s not called for in my solution.

    1. I don’t think you need to “do” much maths at all – just be able to recognise whether 4/5ths is less than or greater than 19/20ths.

  12. As far as I can tell, this can’t be answered. I get that from this we gather that 5 clicks in 5 seconds isn’t one click per second, so Jack’s click rate is either just slower or just faster than that. If given 6 seconds he might be able to squeeze in a 7th click, or he might not make that 6th click before the 6 seconds ends.
    All I can gather is that there is a greater margin of error with Jack, then it’s John, and James is the closest or most accurate click rate to the one-click-per-second.
    A winner can’t be deduced from this.

    1. Well done sir. I suggest you also tell the fence post fans where they can stick them as well.

    2. I think you have to make an assumption that the ‘timing period’ rule applies to the users’ measured click rates too.

  13. 2 seconds for a “duh it’s obvious” answer, another minute staring at it wondering, “is there a trick I’ve missed here?” Then 10 seconds with pen & paper.

  14. Answer guessed almost immediately (<5s), but another 20s to prove with calculation….(helped with the basic concept due to the fact that I had recently replaced my staircase balustrade).
    DS 🙂

  15. Usually the key to these puzzles is to not make any assumptions and read exactly what the puzzle specifically says. Sometimes it can be helpful to write and equation or draw a diagram to describe the conditions specified.

    Too often we read something written quite clearly and make assumptions about what is says, like the assumption that timing clicks in this matter means that it takes each person 1 second to click a mouse.

    **********BIG HINT**********

    For any of the entrants, how long does one click take using the specified timing method?

    1. I second this advice. My first instinct was to draw a diagram, and that really helped me to conceptualize the true nature of the problem.

    2. What is the specified timing method – chronometer, stopwatch, egg-timer? It’s also so confusing.

    1. 2 seconds is way too long. Except that I had to read it twice to make sure it really was as easy as it seemed.

  16. Was the mouse in thursday’s picture with the cat?
    I didn’t go for the immediately obvious wrong answer I sketched out a couple of others before deciding there’s not enough info for an absolutely correct answer.

  17. Got it right away, but then took a minute to verify my answer. It is the reverse of the problem about 2 sharpshooters. One can get off 5 shots is 5 seconds; the other can get off 10 shots in 10 seconds. Which is the faster shot?

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