2016 F5 September exam paper questions ACCA

Hi,

Please see the below question numbers that I am having difficulty understanding the answers to for the Sep 16 exam paper, provided on the ACCA website.

Thank you for your help!

Questions:
1) Do you add in depreciation for life cycle costing and why since it is not a cash flow? I know that in relevant costing we don’t add it in, and thought the same theory would apply here?
2) Why is the contribution used here $18? As we need it PER unit. I understand that 2 y is sold for 1 x but why would we not use $14. Also why have they calculated the weighted figure?
6) Would the answer not be efficiency since we’re talking about input to output, students passing exams is determined by how well they were taught (teachers = input/grades = output)?
10) Why have they taken the NBV as cash flow here?
11) I don’t understand why they have taken the bottleneck as process 2?
20) I have tried to work out the margin of safety and cannot seem to understand how they have come to 84.6%? The BEP I see to be (70/(455/1300)) I know its FC/(TOTAL contribution/TOTAL revenue) but even if I adapt my answer I still cannot get the denominator to 0.7 as they have.