Process Costing and EOQ

Respected Sir, I have two doubts. The first one is with respect to Process costing and the second one with respect to EOQ. Doubt 1 - A firm operates a process costing system. Details of Process 2 for Period one are as follows - During the period 8,250 units were received from the previous process at a value of $453,750, labour and overheads were $350,060 and material introduced was $24,750. (I will not give further information as my doubt relates to the cost not the Equivalent Units) My doubt is why do we add 'materials introduced' ($24,750) to the cost of $453,750 while calculating the cost per unit for materials ? What exactly is the explanation of this 'materials introduced' ? If it means more material is being introduced, then where are the units ? I am assuming the units always go with the materials (as u say in your lectures), so the cost of $453,750 is for materials. DOUBT 2 (EOQ) - A company uses Material Z (cost $3.50 per kg) in the manufacture of Products A and B. The following forecast information is provided for the year ahead : Product A Product B Production (units) 25,300 10,100 Material Z usage (kg per completed unit, net of wastage) 1.8 3.0 Material Z Wastage (%) 5 11 (I won't give further information as my doubt relates to annual demand) My doubt is, while calculating the total requirement for material Z (in kgs) for the year ahead, why are we taking gross of wastage ? Meaning we are adding back the 5% wasted for Product A and 11% wasted for Product B. If we are forecasting 5% is going to go waste, then whats the point of ordering it ? I hope my doubt is clear.