Happy​ Trails, Inc. manufactures railway coaches and uses the FIFO method of process costing to record costs. The WorkminusinminusProcess Inventory of the Heating Department on October 1 was 73​% complete for materials and 23​% complete for conversion costs. On October​ 31, its ending WorkminusinminusProcess Inventory was 80​% complete for materials and 43​% complete for conversion costs. This means that for the ending​ inventory, % of the materials and​ % of the conversion costs were added during October.

80 % of materials ;  43 % of conversion costs

Explanation:

The FIFO method traces equivalent units for materials and conversion costs for the following categories :

So the units not completed from last months are the first to be completed during the month (hence To finish Opening Work in Process). During the year there are units started and completed (hence Units Started and Completed) and units started that never gets completed (hence Ending Work in Process units).

All these physical units need to be expressed to the percentage of work done on them - equivalent units.

The question is focusing on Number 3 - Ending Work in Process units. So 80 % of materials and 43 % of conversion costs were added during October for these units.

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