In economics, the most economical quantity Q of goods (TVs, dresses, gallons of paint, etc.) for a store to order is given by Wilson's lot size formula Q = √2KM/h where K is the cost of placing the order, M is the number of items sold per week, and h is the weekly holding costs for each item (the cost of storage space, utilities, taxes, security, etc.).
(a) Explain why ∂Q/∂M will be positive.
(b) Explain why ∂Q/∂h will be negative.