[alThor]

[ QUOTE ]
On the other hand, if you mean reaching 1 below without having first reached 2 below, or vice versa, then it is not obvious, in fact I think it is false, that they are equally likely.

[/ QUOTE ]

Upon reconsideration, I think you're right, which throws off my ROR solution above.

What confuses me, however, is the fact that we satisfy 1-M = 0.5+Y/2 in the two solutions posted.

The solution for "Y" makes sense to me, and I consider that to be the answer to the "right" question (i.e. the best well-defined question one can form based on the wording, starting at zero and only looking forward).

However the equation (1-M) = 0.5 + 0.5Y assumes that "half" the integers are below zero (or any arbitrary lower bound), while half are above. What confuses me is that the "percentage of integers that are below zero" isn't well defined. (E.g. One can map the odd positives into all the negatives, and thereby "prove" that two thirds of the integers are positive.)

So how did the solution for M happen to satisfy 1-M = 0.5+Y/2? The solution for M must have had a hidden assumption that half the integers are negative?