It’s the Friday Puzzle!


It has been quite a week.  For anyone that missed the fuss, we announced the launch of Dream:ON, our new iphone experiment into dream manipulation.  It was been covered by media across the world and we hope that you can take part.

So, to the puzzle….

Yesterday I bought a strip of multi-coloured cloth.  One third and one quarter of it is black, and the other 8 metres are red.  How long is the strip?

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 USA here). You can try 101 of the puzzles for free here.


67 comments on “It’s the Friday Puzzle!

  1. The Masked Twit says:

    Red and black?

  2. Ale says:

    One minute.

    • Anonymous says:

      So one third and one quarter added is seven twelfhs. So the red material is five twelths = 8 meters. Easymaths

    • Neil says:

      Unfortunately you missed the “As ever, please do NOT post your answers”. What is it in you that feels the need to show off and spoil this competition?

    • historyslc says:

      Brilliant anonymous. In trying to show how smart you are, all you have done is show that you are an idiot!

    • Mervulon says:

      Someone really needs to block Anonymous. There is only ONE RULE here, and it’s more than they can handle…

  3. drsuzanne says:

    Yep. A couple of minutes. Nice way to start the day 🙂

  4. Mickey D says:

    One minute

  5. Anonymous says:

    I think I’ve got it, I will probably forget to check the answer Monday now anyway.

  6. AMWhy says:

    Nice little piece of mental arithmetic. Took a little under 20 seconds.

    • Jerry says:

      I set up the calculations in my head, then used the calculator app on my computer to do the actual arithmetic.

  7. Timdifano says:

    About a minute, but had to use pencil and paper…too early in the day

  8. Nigel says:

    Simple maths, took one minute.

  9. Tom Pedersen says:

    About a minute. Used pencil and paper.

  10. Mark says:

    Well I got it and I’m not usually good at mathematical ones. Now the long wait to find out the “obvious” answer that I didn’t see (the one that tells me that I did in fact get it completely wrong)!

  11. Anonymous says:

    Got it in 0.1256 seconds using a flagpole and a photocopier

  12. Daryl says:

    none too bad. so many ways to come to the same conclusion.

  13. Julia says:

    needed a calculator. 2 minutes.

  14. Chris says:

    If you ignore the maths, it’s obvious! 2 seconds.

  15. Anonymous says:

    14 seconds. Used a tape measure, and measured the bi-hued cloth.

  16. Lazy T says:

    Too easy, so lets pick nits….
    Is the 1/4 is within the 1/3 or are they two distinct bits?
    Are they stripes or bands?
    Is the material looped like a moebius?

  17. ivan says:

    If that is a reasonably practicable way to describe its proportions, it is a very unusual piece of multicoloured cloth.

  18. Think I’ve got it. 10 mins after a few wrong tries and a hangover.

  19. CrazyHorse says:

    It can be either 1/4+1/3 of the total, or 1/3 of the total, or 1/3 +1/12. All of those fits with the statement…

  20. Chris says:

    It took me ages with pen, paper and calculator to get an answer. Then it dawned on me…

  21. pdurrant says:

    How nice to have one that can be easily done in a couple of seconds without resorting to paper and pen. Unless you misread the question, of course!

  22. Matt says:

    Easy, as always a mathematical one that has nothing to do with maths, you have to think latterally and ignore any numbers.

  23. Tom (iow) says:

    I have the mathematical answer, and then after reading teh comments, the lateral answer. However I do not agree that the former is misreading the questions. The lateral approach makes an assumption about the way the cloth is being bought, which we don’t know is teh case.

  24. mittfh says:

    Shows how long it’s been since I added fractions – I used Excel to add them, then perform two additional calculations to arrive at the answer.

  25. Add the fractions or take them as two individual statements, fine. But I truly don’t see how to treat this laterally. To me, the critical word is “other”.

  26. Francis says:

    There’s missing information on the color pattern! Is it striped? If so, in which direction? If not, then how is it?

    Without this information, all we can deduce is that the strip is at least 8 metre long. Or am I missing something?

  27. Anonymous says:

    I guess there is something in the wording, because I don’t think this is just a simple math question.

  28. One Eyed Jack says:

    Got it.

    I predict a debate on Monday.

  29. Jerry says:

    I think that I solved it in under a minute. It was so easy that I am wondering if there was some trick that I missed. Converting the fractions to percentages was a help.

  30. Nelis says:

    Easy peasy with a little Junior High algebra. A minute including verifying the result via calculator.

  31. Niva says:

    Less than a minute, assuming there’s nothing tricky that I missed.

  32. dharmaruci says:

    this is a puzzle to me. if there are two stripes running the length of it, both black, and one is 1/3 and one is 1/4 of the width. i understand that. but how can the rest be 8 meters long? unless it is all 8 meters long.

  33. Sari1967 says:

    I have the answer as long as there were only 2 colours.

  34. AL says:

    “So one third and one quarter added is seven twelfhs. So the red material is five twelths = 8 meters. Easymaths”

    So says Anonymous, and is accused of spoiling, But the wording of the question says “the OTHER 8 meters is red”. So reading this as the meaning is implied, ie that you have two 8 meter halves, the first half of the strip is 8 meters, and the second half is 8 meters! So Anonymous has to fit that statement too. ie There are three possible answers so far: 8 meters, as just stated; 5x/12 = 8 meters (Anonymous); and 7x/12 =8 meters.

    The Wise Man will tell us on Monday, but Anonymous hasn’t spoiled it yet…

    • Chris says:

      this only works if you use the word “other” as something, er, other than what the word means in english – i.e., as an adjective referencing the part that came before. here, to be grammatically correct, other can only refer to the black portion of the cloth.

      of course, pi is exactly equal to 22/7, so all bets are off.

    • Maths nerd. says:

      Pi is NOT exactly equal to 22/7. Pi is irrational. (It cannot be written as a fraction). Although it can be written as a series of infinite fractions: pi = 44 – 4/3 + 4/5 – 4/7 + 4/9 – 4/11 + …

  35. AL says:

    Oops 8 plus 8 = 16, sorry.

  36. edwardv says:

    I’m suspicious of the wording. Why “and” and not “plus” for the fractions? Why “other” and not “remaining”? I hope this isn’t poor wording trying to be tricky.

  37. Ian says:

    Hmm, intriguing. Thanks for another good one, Richard 🙂 Arrived at the answer in maybe thirty seconds, off the top of my head, although something in the wording’s causing me to wonder if I’ve missed something, so I’ll be pondering it some more, just in case. Thanks again and have a fascinating and relaxing weekend 🙂

  38. Jenifer says:

    Got it. Took about 30 seconds. 🙂

  39. the app freezes when i say no to the question about weather I have heard the sounscape, in the dream diary (iphone app)

  40. JohnLoony says:

    It took about 30 seconds to get the answer, assuming that all the assumptions which I made about the wording and meaning of the question are correct, and/or accurate, and/or what was intended to be understood by Richard.

  41. Ronda says:

    I had a blank moment, so it took me about a minute and a half.

  42. Zach says:

    Unless I’m having a slow day (wholly possible) there are two ways to read the question. One third and an ADDITIONAL one quarter, or the quarter is a part of the third.

  43. Stephen says:

    I’m going to go out on a limb and predict much consternation and debate on Monday.

  44. Hal Harris says:

    I believe I have it. Took a minute on paper.

  45. Charles Sullivan says:

    Solved! 5 minutes

  46. Pc problemerfixes her…

    […]It’s the Friday Puzzle! « Richard Wiseman[…]…

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