Throughput using marginal costing principles

The question as you have typed it is not a question on throughput accounting at all. It says 'using marginal costing principles', which means to use normal key factor analysis (which I explain in my free lectures on throughput accounting - I do an example first using key factor analysis, and then afterwards using throughput accounting). So it is not a question of finding bottleneck hours, but the limit on hours is certainly needed and is given in the question as being 32,000 hours.