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'Snake-Eyes ' Joe (Posted on 2008-07-28) Difficulty: 3 of 5
"Snake-Eyes" Joe introduced a die of his own into a game of chance.

He was subsequently challenged that the die was biased.

Very rigorously test to see if there are grounds to substantiate this claim; don't accept just two or three trial runs. Are you able to offer a theoretical model consistent with your findings?

Test "Snake-Eyes" Joe's Die with this simulator which has a run of 60,000 at a time:

No:123456Total
Scores 0 0 0 0 0 0 0

Note: the data changes with each subsequent mouse-over visitation to the link.

See The Solution Submitted by brianjn    
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Solution Solution | Comment 5 of 14 |
Looking at the Javascript code of the simulator, one can see that the condition where the variable is tested for '1', unlike the other five values, every tenth occurance the value is randomly generated the random function is called a second time before the value is tallied, thus reducing the chance for a '1' in generation in respect to the other five values.

{
    a=Math.random();
    g=Math.floor(a*6+1);
    if (g==1 && tn==10)
    {
      tn=0;
      a=Math.random();
      g=Math.floor(a*6+1);
    }

    if (g==1){t++; tn++; }
    if (g==2){u++; }
    if (g==3){v++; }
    if (g==4){w++; }
    if (g==5){x++; }
    if (g==6){y++; }
}

  Posted by Dej Mar on 2008-07-30 09:26:26
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