Alice is playing checkers against a computer and has won 8 games out of the 12 she's played so far

I do not know what kind of answer you may want but here is a few you might be asking for

(1). Every 12 games Alice wins 8 games and looses 4. (8/12)

(2). Alice wins 2/3 games against a computer. (8/12)

(3). Alice wins 66% of games she plays against a computer.

There you go.