Pottle Ice Cream uses a mixing department and a freezing department to produce its ice cream. Its process costing system in the mixing department has two direct materials cost categories (ice cream mix and flavourings) and one conversion cost pool.

The following data pertain to the mixing department for April 2018:

Work-in-process, 1 April 0

Started in April 10 000 litres

Completed and transferred to freezing 8 500 litres

Costs:

Ice cream mix $27 000

Flavourings $4 080

Conversion costs $53 700

The ice cream mix is introduced at the start of operations in the mixing department, and the flavourings are added when the product is 40% completed in the mixing department. Conversion costs are added evenly during the process. The ending work-in-process in the mixing department is 30% complete.

Required

1. Explain using a diagram how to calculate the equivalent units for direct materials (DM) when the ending work-in-process is 30% complete, in the following situations:

a) 100% of DM is added at the start of the process.

b) 100% of DM is added at the end of the process

c) 100% of DM is added when the process is 40% completed