Strange to get a fuel flow question, I thought those were only in performance, also due to the fact its CPL, all of the questions I got in mine said charter, I never ran into one about private ops. (sat performance a month ago, haven't done NAV yet) you are right about only needing 45 mins for private, however they usually include something in the exam saying "company procedure is to include reserve fuel in accordance with CAAP 234-1" implying that you need to include a variable reserve also.