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points or pigeons in square? (Posted on 2019-08-05) Difficulty: 2 of 5
Given 5 points inside a square of side 10 cm, what is the probability that at least two of the points are within 8cm of each other?

No Solution Yet Submitted by Danish Ahmed Khan    
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Solving the right problem | Comment 4 of 8 |
Sorry, I solved the "greater than" 8 case rather than the "less than"  8 cm case. 

Changing the simulation slightly, I found the likelihood that the pigeons are pigeon-holed just right by using 100 million trials each time, where "good" means that all 5 managed to be 8 cm from each other:

 prob. = 0.99999917

Looking at the probability it won't happen is more intuitive:
0.00000083 +/- 10%
Here are some runs:

8 64

 good =           70

100000000 0.0000007000000

 exp?

8 64

 good =           76

100000000 0.0000007600000

 exp?

8 64

 good =           98

100000000 0.0000009800000

 exp?

8 64

 good =           88

100000000 0.0000008800000

 exp?

8 64

 good =           83

100000000 0.0000008300000

 exp?

8 64

 good =           77

100000000 0.0000007700000

 exp?

8 64

 good =           86

100000000 0.0000008600000

Edited on August 5, 2019, 8:59 pm
  Posted by Steven Lord on 2019-08-05 20:18:41

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