Budgeting

Hi my dear Tutor, I need your help Budgeted sales of X for december are 18000 units.At the end of the production process for X, 10% production units are scrapped as defective.Opening inventories of X for December are budgeted to be 15000 units and closing inventories will be 11400 units.All inventories of finished goods must have successfully passed the quality control check.WHat is the production budget for x for december? Budgeted sales-18000 add closing stock-11400 less opening stock-15000 equal budgeted production-14400 Why we do not take into consideration the normal loss of 1800(18000*10%) in budgeted production ? From my comprehension, It should be based on production units or production inputs and in this case it is budgeted sales that is why normal loss is not taking into account.this is my understading, i do not know whether it is right or not, but need your help too Thanks in advance