  In this article, we give a proof of the link between the zeta function of two
families of hypergeometric curves and the zeta function of a family of quintics
that was observed numerically by Candelas, de la Ossa, and Rodriguez Villegas.
The method we use is based on formulas of Koblitz and various Gauss sums
identities; it does not give any geometric information on the link.
