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Ducks in a pond (Posted on 2023-01-24) Difficulty: 3 of 5
3 ducks have landed in a circular pond. What is the probability there is a diameter such that the semicircle on one side contains all of them?

Repeat for 4 ducks.

Note: consider the ducks to be randomly chosen points in a circle.

No Solution Yet Submitted by Jer    
Rating: 5.0000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
numerical integration with 4 ducks | Comment 5 of 17 |
With the bug gone and a 4th duck added:

ct=0; hit=0;
for a=0 
  for b=0:.5:359.5
    for c=0:.5:359.5
      for d=0:.5:359.5
        ct=ct+1;
        set=sort([a b c d]);
        aa=set(1);bb=set(2);cc=set(3);dd=set(4);
        diff=[bb-aa cc-bb dd-cc  aa-dd+360];
        if max(diff)>180
          hit=hit+1;
        end
      end
    end
  end
end
disp([hit ct hit/ct])

results in

 185847839    hits out of  373248000  cases for a mean of 0.497920522012174

which is close to 1/2.

  Posted by Charlie on 2023-01-24 11:10:00
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