In this paper it is proved
that a C∗-algebra A is strongly amenable iff A satisfies a certain fixed point property
when acting on a compact convex set, or iff a certain Hahn-Banach type
extension theorem is true for all Banach A-modules. It is proved that a
C∗-algebra A is amenable iff A satisfies a weaker Hahn-Banach type extension
theorem.