Two to one is usually what I recommend, but three to one (or more) is better.
Mollies will interbreed fine (they're all from the same wild stock), as Richard said. Also, as Richard said, there will be a problem of bad mutations due to inbreeding, so if you breed your mollies, you should try to continually change out some of the stock.
In the case you suggested, you'll likely end up with a few silver, a few black, a few dalmations, and probably a cremesicle or yellow or some other odd color. Nearly every molly has a touch of "other color" DNA in it, since it's nearly impossible to breed them true unless you dedicate a tank to a single color for many years. All it takes is a few minutes in a tank with cremesicles, and a platinum female could be loaded with orange fry that she could drop anytime in the next several months, perhaps even right into your dedicated platinum tank.
Oh, and (also, like Richard said), there aren't dumb questions.
Huh, so chalk my post up to say "Richard's right"
