In Israel we say "אוקיי" (literal transcription of "OK") a lot, so yes you can. :)
Since you're studying Hebrew, I just want to point out that we say OK alot, but it's slang. So don't try to use it in a formal context, or as an answer in Duolingo.
@CJ.Dennis Oh, right. Thanks, man! Now, after one year, it also sounded to me very odd. I'm not a native, sry. Anyways, I edited it!
Not really. Good is טוב. While they are similar in meaning, and sometimes used interchangably, that wouldn't be a correct translation.
I'm glad they have "all right" as an acceptable answer, since it is how we write it in English. "Alright" is slang (if you consider a frequently-used misspelling that happens to be pronounced the same as the proper one to be slang), just so we're clear.
I feel like הכול בסדר is a more accurate translation versus just בסדר.