I heard that the chance to generate a block is like playing a lottery, like the odds are 1 in 8,000,000. Is this true?
Sort of. For pooled mining, 300MH/s means you're checking 300,000,000 hashes every second to find a valid share, and should get about 4 - 4.5 shares a minute. A share is anything with a difficulty >= 1. If the share's difficulty is over 4.85 million (the current difficulty), then it's a successful block.
For solo mining, we don't care about diff=1 shares. All we care about are the diff>4.85million, or the block solvers. And yes, a diff=4.85million share will pop up about once for every 4.85million diff=1 shares.
So as far as the lottery analogy is concerned, it's more like 1 in 4,850,000, but that lottery happens 4-5 times a second, not once per day like the PowerBall.
4-5 times a second means 84500 (seconds in a day) times 3 which is 338000 and 4,850,000 divided by 338000 is 14, so that's a 1/14 chance a day. So basically 1 block every couple weeks. But somethin' tells me it's a lil harder than that. What do you guys think about this?