Someone explain this answer to me......

lafrentz06

When Geribaldi is
done there are 3 pieces of string of length 2; no probability
involved. When connecting the pieces there are 3 possible loop
sizes: 2, 4 and 6.

There are (6 choose 2) = 6 * 5 / 2 = 15 choices for knots among 6
string ends. There are (4 choose 2) = 4 * 3 / 2 = 6 choices for
knots among 4 string ends. And there is one choice among 2.

3 of the choices on 6 string ends produce a loop of length 2. So,
on the first pick, 3/15 of the time a loop will be created.
Within that 3/15 of a time, 2/6 (two pairs among six left) of the
time another loop of length 2 will be chosen. So, 3/15 * 2/6 =
1/15 of the time three strings of length 2 will be created. 3/15
* 4/6 = 4/15 of the time first a length 2 is chosen and then a
length 4. Now let's go back to the 12/15 of the time when a
length 4 string is created. Only two choices will produce two
strings; the two that would create a loop. So, 12/15 * 2/6 =
4/15 of the time a length 4 loop is created and then a length 2.

So in conclusion, we have a 1/15 probability of three 2's, 8/15
probability of a 4 and a 2, and the remaining 6/15 = 2/5
probability of a single 6. I suppose it isn't intuitive that the
chance of a getting a single string is so much higher than the
chance of getting 3 separate strings.