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Heh heh, bet you can't work this out! :P

  • 20-04-2000 3:12am
    #1
    Registered Users, Registered Users 2 Posts: 21,264 ✭✭✭✭


    You have two pieces of string. All you know about the string is that each piece takes exactly one hour to burn from end to end.

    The rate of burning is not necessarily constant at each point in the string, however, so one half might burn up in, say, ten minutes while the second half would burn up in fifty minutes.

    You have some source of fire.

    Use the fire and the strings to measure a time interval exactly forty-five minutes long.


Comments

  • Registered Users, Registered Users 2 Posts: 4,162 ✭✭✭_CreeD_


    Light one at both ends, it'll burn out in half an hour.

    Fold the other in two and light it at both ends again as soon as the first one is finished. (Okay this is a wweak link, but you 'should' get equal times across 4 strands - if not count the time difference between the first strand burning up and the last, the median time should be 15 minutes).
    Or, neater, if you're allowed to cut the 2nd string, do so. Then burn each strand at both ends, again taking the median time between the first to die and the second as 15 mins.

    [This message has been edited by _CreeD_ (edited 20-04-2000).]


  • Registered Users, Registered Users 2 Posts: 21,264 ✭✭✭✭Hobbes


    Both strings burn at different speeds across the whole string, so that wouldn't work. tongue.gif


  • Closed Accounts Posts: 1,484 ✭✭✭El_Presidente


    Tell us oh wise one


  • Closed Accounts Posts: 577 ✭✭✭Chubby


    Light both end of 1 string so it'll burn out in 30 mins.
    Light one end of the 2nd string.
    When the 1st string burns out, light the other end of the 2nd string.
    15 mins later, the 2nd string will burn out giving you 30+15=45mins.
    What do I win?

    [This message has been edited by Chubby (edited 20-04-2000).]


  • Registered Users, Registered Users 2 Posts: 21,264 ✭✭✭✭Hobbes


    Congrats. smile.gif You win your own Kiki Oni. tongue.gif

    kiki1.jpg



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  • Registered Users, Registered Users 2 Posts: 4,162 ✭✭✭_CreeD_


    Actually it would work , you'd just have to be accurate with your median count.
    But Chubbys answer is a lot neater.

    Just to prove I'm not completely barmy:
    After folding or cutting the 2nd string into A and B pieces. Say A=20 mins, B=40 mins (Just hypothetical). Burning each at both ends gaurantees you 50% of the total burntime. so we have A=10 mins and B=20 mins. Since we lit both ends of each strand at the same time, we take the median between A burning out and B, = 15 mins.
    Bloody awkward though.


  • Closed Accounts Posts: 577 ✭✭✭Chubby


    After folding or cutting the 2nd string into A and B pieces. Say A=20 mins, B=40 mins (Just hypothetical). Burning each at both ends gaurantees you 50% of the total burntime. so we have A=10 mins and B=20 mins. Since we lit both ends of each strand at the same time, we take the median between A burning out and B, = 15 mins.
    Bloody awkward though.

    Well, that does work but you need an additional item. You'll need a stopwatch to time how long it takes each strand to burn out and if you have a stopwatch in the first place... wink.gif

    Kiki Oni? Who's that? She's dressed like one of the characters from DarkStalker!



  • Registered Users, Registered Users 2 Posts: 21,264 ✭✭✭✭Hobbes


    Originally posted by Chubby:
    Kiki Oni? Who's that? She's dressed like one of the characters from DarkStalker!


    She's from Lum the mad site. She did a news report on a Japanese server update...
    Kiki writes to explain the strange occurence in a previous update which involved oni, beans, and the like:

    hehe for question i can answers!!

    first: oni is monster like orc but red and blue. in the winter come in home for after breaking...like robbers not modernized by systems of effect! then setubun to throw out!!! OUT OUT!!! >_<

    second:momotaro is come to attakk oni. old man is cold and need wood for hot to fire....... old lady who washing spots peach and it is mototaro!! later to kill demon king!!! for party once even i drss like demon king!!! ^-^ LOOK (see picture)

    second: oni are goned in spring festivl... event to throw out the disengaged from homes with mame... (next month to make bean jam with same beans!!)..it is excite very much with celebrate. (w

    so there is oni and setubun and hope to all tales again in coming months!!! bye!!
    thx (w

    PEACE AND HAPPY IN BRITANNIA!!

    KIKI


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