dont worry yourself about understanding the concepts because they dont ask about it in the exam. Just remember the answer to the question and you'll get it right.Its the same as compass swing questions that take up about 15 pages in the notes, have you ever seen a question that asks for co-efficiency of a , b and c? No , and i dont think your likely too.Just concentrate on the practical side of navigation and you wont go far wrong.You are also likely to get no more than 2 questions on PNR and CRit point plus 1 on relative velocity and the rest made up of whizz wheel questions and a bit of INS nav with learnt answers.. .. .i have taken this exam twice so hope to get through this time , but my advice is to get up to speed on plotting etc and be a dap hand at whizz wheel.. .good luck