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Bean weight brain teaser

  1. Aug 12, 2004 #1
    there are 10 boxs of beans. in each box there are 10 beans. of the 10 boxes, 9 of them have beans weighing 1 gram each and the remaining one have beans weighing 0.9 grams each. the boxes are now placed side by side randomly. you can only use the weighing machine once, find out which box contains the beans that weigh 0.9 grams.
  2. jcsd
  3. Aug 12, 2004 #2
    1+2+3+4+5+6+7+8+9+10 = 55

    -- AI
  4. Aug 12, 2004 #3


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    Staff Emeritus
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    Gold Member

    Damn, Tenali's fast, eh ? :wink:

    Say, Tenali.

    <Select below>

    Why don't you write the answer down in white so others can still work on it if they don't want to see the answer.
    Last edited: Aug 12, 2004
  5. Aug 12, 2004 #4
    omg tenali u again... lol guess i'll have to come up with something harder :)
  6. Aug 12, 2004 #5
    I try to be as cryptic in my answer as possible so as not to give away anything and still put out a solution. Though I will keep it in mind to post in white next time i give my answers.
  7. Aug 17, 2004 #6
    Please explain th e solution, I don't get it.

  8. Aug 18, 2004 #7
    Vague Hint
    Assume that u have 10 robots and each robot is assigned one bean box. the 10 robots are given different numbers say x_i. Each robot then just selects a bean from its corresponding bean box and computes the the product w_i*x_i .... then suppose we add up all this computed outputs ..... what can we expect if
    1> all w_i are same (or 1 gram as in this case)
    2> one of w_i is not same (or .9 grams as in this case)

    i will put out a more specific hint later but think on the above it can help u solve a lot many problems .....

    -- AI
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