Maths puzzle: Gender based seating preferences on Tube trains.

As I was about to get off the Tube this morning, I noticed that there were six women on the row of six seats opposite me and five men and one woman on the row on which I was sitting. None of the people concerned appeared to be travelling together, it was twelve individuals.

I see this quite often, and I wonder to myself, is this because women have a preference for sitting next to other women rather than next to men (perfectly understandable, women use less space etc) or is this purely a random thing? (Let's ignore the possibility that men prefer sitting next to other men, because this is merely the equal and opposite).

Now, if we have a fixed pool of five men and seven women, and they sit down at random, we can calculate the probability of there being six women on one row*, it is 16.3% (Method A).

But this is a meaningless calculation because there is no fixed and limited pool: hundreds of people will get on and off each Tube train in a forty-minute journey. Just because the last passenger to sit down was a women does not materially affect the odds of the next passenger being a man or a woman (like tossing coins rather than pulling coloured balls out of a hat).

So the other way of calculating the odds of having six women in a row is 0.5^5 = 3.125% (Method B).

COUNTERPOINT: as Kj in the comments says "The objections to Method A are correct, but then again, if there is a 0.5 chance of every passenger being either sex, on average the pool of potential sitters is also roughly 50/50".

I definitely see this phenomenon (all women on one row, all men on the opposite row) quite often, certainly about once a week (ten journeys) and more often than once or twice a month (forty journeys).

There again, I only really notice it if there is a clear pattern, which might only exist for part of the journey. I'll have to start running a tally, but my question(s) to the great minds reading this is:

Which is the better way of calculating the odds of six women (each travelling alone) ending up sitting next to each other on a six-seat row? Method A or Method B, or is there an even better way, Method C, and if so, what is Method C?

Supplementary question: if you knew how often this "all women" pattern emerged, would you be able to work out the marginal preference of women for sitting next to women?

* There are 7 permutations of having 6 women on one side and one on the other, 21 permutations of 5 and 2; and 15 permutations of 4+3 = 43. 6/43 = 16%.