Cost accoutning

Hello sir ,

Please help me with the below question .

Material input 200 kg at $4 per kg
Labour input 100 hours at $15/hr
Dept overhead $1000
Trfr to finished goods 150kg

Normal loss is 10% of input .
Losses are identified when the process is 50% complete.
There is no opening and closing work in progress .
What is the total cost of the completed unit ?

In the above question ,how do we get Actual loss 50 kg ?