Is a fast considered valid if the bleeding stopped before Fajr and the ghusl was performed four hours after Fajr?

The ghusl (ritual bath) should have been performed immediately upon seeing purity, without delay. The prayers missed after seeing purity but before performing ghusl must be made up. As for the fast, it is valid as long as the intention was formed before Fajr, because ghusl from menstruation is not a condition for its validity.