Baiscially questions will be asked based on the area of industry to which you are attending interview for. In manufacturing industry itself there are many segments and first before going for interview, just spend some time on looking at company profile (through net if website available or try to view some similar company profile).You will become familiar with the process, techniques, cost centers and different cost units which will normally exisit in such industry. Then yoo need to prepare yourself in areas of - Inventory management, stock systems (registers,bincard,audit etc),process techniqes, cost analysis - man hour rates,machine hour rate,production budgets,labour invovled,purchase and conversion of rawmaterials in to finished goods etc. Basically they will not look in to your theoritical aspects they will give u real time senario and you should be able to convince them with a proper answer. You need to relate theory to practical problem. Costing person role in an firm is to manage,control and reduce cost so be prepared in these areas.
When the total factory overheads is expressed in terms of total labour hours required to complete the task, it is called as labour rate. It is expressed as (Total Factory Overheads divided by Total Labour hours). In simple it shows the percent of labour rate absorbed per hour in the total overheads. When the total factory overheads is expressed in terms of total machine hours (number of hours machine is put to use in order to complete the given task) it is termed as machine hour rate. It is expressed as- Total Factory Overheads divided by total machine hours. One point. to be kept in mind here is that while caluclating total machine cost we need to consider all the cost which is incurred to brining the machine to operating conditions and also should make necessary provision for depreciation after considering scrap value.
So, accordingly while selecting the system of machine hour or labour rate you need to know the investment patter. If it is a capital intensive industry then machine hour rate method is more appropriate and if is a labour intensive industry then labour rate method is more appropriate.