Throughput accounting question

Hello John,

I have a question regarding Throughput accounting topic. Namely, as you mentioned the underlying assumption that of T.A. is that all costs are fixed on the long run except direct material cost which may be considered truly variable.

I have ran into this kind of question while preparing for my exam:

Company makes and sells two products A and B, each of which passes through the same automated production operations. The following estimated information is available for period 1:

Product Unit data A B
Selling Price 96 112
Direct Material Cost 3.2 64
Variable prod. O.H. 52.80 8
Machine h per unit 0.4 0.24

Total Fixed production OH cost is 2,352,000. This is absorbed at an average rate per hour based on expected production levels, A 192,000 units and B 72,000. What are the Throughput Accounting Ratios of A and B?

What confused me was the mentioning of Variable Production Overhead cost. I have included it into Total Factory Cost when calculating Cost per Factory hour together with the Total Fixed production OH, while in the solutions I saw only the latter was used.
I thought that the examiner wanted these Variable costs to be included also (since those were not Direct Material Costs, the only variable costs under T.A. theory) because maybe those relate to labour, or something similar…
In short, what is your rationale behind is and what is your advice how not fall into this kind of trap on the exam? I assume one of the answers is to practice as much questions as possible… 🙂
Thanks in advance!
Rgs