Try thinking about this more generally. You have an object moving in a circular path (in this case in orbit around the moon). In order to maintain this path there must be a centripetal force acting, in this case gravity. Write down the gravitational force between the object and the moon and equate it to the centripetal force, the answer should then be just a few lines of algebra away.
interesting, a (centripetal) = v^2 over r, where r is mean radius of moon, and a (centripetal) is 1.6 m/s^2, one can solve for v.
I think I got it, thanks buddy.