"This powerful prayer is very effective in examinations. It has to be said before appearing in the examination. There are two variants to this prayer. Both the prayers are equally effective. You can choose any one of these:"
First Prayer O Great St. Joseph of Cupertino who while on earth did obtain from God the grace to be asked at your examination only the questions you knew, obtain for me a like favour in the examinations for which I am now preparing. In return I promise to make you known and cause you to be invoked. Through Christ our Lord. St. Joseph of Cupertino, Pray for us. Amen. Second Prayer O St. Joseph of Cupertino who by your prayer obtained from God to be asked at your examination, the only preposition you knew. Grant that I may like you succeed in the (here mention the name of Examination eg. History paper I ) examination. In return I promise to make you known and cause you to be invoked. O St. Joseph of Cupertino pray for me O Holy Ghost enlighten me Our Lady of Good Studies pray for me Sacred Head of Jesus, Seat of divine wisdom, enlighten me. “Remember, when you succeed in the exams then you should thank St. Joseph of Cupertino in the Newspaper.”
_…_I imagine AF would be fine too.