I don’t have a copy of the CFA Institute books at hand, but I’d imagine that if _ q _ is the order quantity, then we assume that we sell uniformly throughout the year and replenish just when we run out, so our average inventory is _ q _/2, and our storage cost is 10% × _ q _/2 = 5% × _ q _. The number of orders is 10,000 ÷ _ q _, so our total cost is:
_ C _ = 5% × _ q _ + 10,000/_ q _
When you compute d_ C/dq _, set it equal to zero, and solve for _ q _, you get:
_ q _ = √(10,000/5%) = 2,828.
(Because you pay the full order cost no matter what size the order is, you’ll want order sizes that divide evenly into 10,000: check the cost of 2,500 and 3,333. You’ll find the minimum cost at 4 orders of 2,500 each.)
Exactly my point… why would I waste time helping someone with some random concept when I can’t even remember my own CFA crap :). pierrewoodman was shitting his pants, thinking this was from the curriculum.