The exam will be approximately 75% questions about multi-engine theory.
Almost right. The pass mark is 75% whereas the ratio of generic MEP to type specific questions is 60%/40%. The exam should comprise between 40 and 60 questions, depending on the complexity of the specific type used. Nothing should appear in the 60% generic questions that has not been taught in the 7 hrs theoretical knowledge training and nothing should appear in the type specific questions that is not included in the POH/AFM (see CAP601, Ch 5)