> Nope, wrong again.
>
> THIS time, I was figuring it with both masses the same at the start, instead of one being twice the other one.
>
> So I'm pretty sure now I was right THE FIRST DAMN TIME.
>
> This is what I get for constantly second-guessing myself when it comes to math.
>
> -- Dave

Actually, I think you were right the second time...

Set M equal to the mass of the smaller star, and you get the equation:

2M/4^2 = M/x^2

where 4 lightyears is the distance to the massive star, and x is the distance to the lighter star. You then get:

M*4^2 = 2M*x^2 , 4^2/2 = x^2 , x = sqrt(8) = 2.8

At least I think that's it. I'm going to fail my AP Physics test next week anyways, so if I'm wrong it doesn't mean much.