English to Spanish Law/Patents Certificates, Diplomas, Licenses, CVs

Estoy traduciendo un certificado académico de la Universidad de Bangor en Gales. Este es el contexto:

"To be eligible for the award of an Ordinary Degree, a candidate must have attained an *overall average pass mark* in a total of 180 credits at Level HE2/HE3 (weighted equally) with 60 credits of these at Level HE3".

Más contexto:

"For the purposes of overall assessment, a candidate's performance in each module is shown as a number of marks out of 100, with the pass mark set at 40. Marks are reported as integers.
The minimum pass level for progression between levels is an average of 40% over all modules with marks of 40% or more in all the core modules for the course together with 40% or more in modules worth at least 80 credits, provided that the candidate exceeded the minimum acceptable mark in the remaining modules".

From what I understand, a student could get 30% in some subjects, 70% in other subjects and end up with an average pass mark of 50%. That just doesn't sound right to me.

My attempt: "una nota media global de aprobado en un total de 180 créditos".
Thanks a lot.