Process costing using the weighted average method

Thank you sir for the lectures. Really informative.

I must ask though how come in the example you calculated, you still considered the started work in progress materials as 15000 units yet when it came to the closing work in progress labour and overheads, you considered the equivalent units of 25000?

I expected to have 0 units under opening work in progress for materials, equivalent units for opening WIP for labour as it was done for the closing WIP in for labour &overheads and materials.