Thanks Alan, I did it exactly the same way BUT
can you see any way of getting the total number of paths possible?
I suppose you could do it backwards.
Any individual path has the probability of $${\frac{{\mathtt{1}}}{{{\mathtt{2}}}^{{\mathtt{6}}}}}$$
So
$${\frac{{\mathtt{1}}}{{{\mathtt{2}}}^{{\mathtt{6}}}}}{\mathtt{\,\times\,}}{\mathtt{x}} = {\mathtt{1}} \Rightarrow {\mathtt{x}} = {\mathtt{64}}$$
So there must be 64 possible paths taken, 22 of these are favourable outcomes
so P(ending at startpoint) = $${\frac{{\mathtt{22}}}{{\mathtt{64}}}} = {\frac{{\mathtt{11}}}{{\mathtt{32}}}} = {\mathtt{0.343\: \!75}}$$
This is interesting -
I cannot remember ever using probability backwards like this to work out the number of possible outcomes.