There is an annual demand of 500 items and the supplier offers the prices shown in the table. If the rate maintenance is 20% and the cost of orders is $ 50, what's the size of the optimal batch? What is the cost associated with this policy?

In the third row it means that the first 50 will cost 4100 in total, the other 50 will cost $90 each, and the rest 80 dollars each.

Quantity to buy per lot 1-50 51-100 101 Price $100 50 units $100 and the rest $90 50 units $4100, 50 units $90 and the rest $80