[Edit: I am also new to this forum. I should probably have posted on a sub category]

This is my first post here and I am new to Bitcoin. I have been doing a lot of reading in the past week and have not been able to find the answer to a question that I have.

First of all I have an old computer with a Nvidia in it which gets about 40M hashes. Before you laugh I am just figuring out how to set stuff up and do not expect this thing to do much but waste power.

My question is this: Is it theoretically possible, even if extremely unlikely, that a setup like this can solve a block? More precisely - is every hash just a random guess and is each guess just as (un)likely to be a correct one?

If the answer is yes then what are the odds of a guess being correct? I have heard things like "at the current difficulty it would take 10,000 years..." But I would like to know "at the current difficulty a hash has the probability of 1 in a billion to be correct". Are the odds worse than, say, Powerball?