Budgeting: BPP Kit (15.3)

QT Co manufactures a single product & an extract from their flexed budget for production costs is as follows. Activity Level 80%: DM = 2,400 Labour = 2,120 POH = 4,060 Activity Level 90%: DM = 2,700 Labour = 2,160 POH = 4,080 What would the total production cost be in a budget flexed at the 83% level of activity: (to the nearest $) A 6,266 B 6,888 C 8,586 D 8,688 D is the answer. I've understood the answer completely. They've used those activity percentages as whole numbers and then based their calculations. Direct Material is considered wholly Variable. DM per % of activity = 2,400/80 = 30 Labour & POH is considered semi-variable, therefore using High Low method for combined costs of Labour & POH. Labour & POH per % of activity = (6240-6180)/(90-80) = 6 Fixed Element = 6180-(6*80) = 5,700 I'm confused with some points: 1) They've not mentioned in any way the nature of costs i.e variable, fixed or semi variable. How are we supposed to approach this question? Should we check the behavior by simply checking variations in per unit cost? I supposed Labour Cost Variable and POH fixed at first. 2) They've supposed % as whole numbers. This can be a big confusion. Most of the students will simply divide 2,400 by 80% (not 80), getting 3,000 and keep guessing how they've calculated 30. 3) Last, if it is the way it is here, then is it worth 2 marks? I'm just curious about this one, nothing else..