The German encyclopaedia Der Kleine Pauly s.v. Hypatia gives her date as
370-415, referring to an article "Hypatia" by J.M. Rist in Phoenix 19,
1965, p. 214-225. Unfortunately I do not have access to Phoenix this month,
so I do not know if Rist has further information about her birthdate. I
doubt so, since it is not in Suda.
For what it's worth.
Christian Marinus Taisbak <marinus@private.dk>
Mathematical Sciences in Antiquity
Copenhagen University, Institute for Greek & Latin