The Wilson lot-size formula in economics states that the optimal quantity $Q$ of goods for a store to order is given by
$$
Q=f(C, N, h)=\sqrt{\frac{2 C N}{h}}
$$
where $C$ is the cost of placing an order, $N$ is the number of items the store sells per week, and $h$ is the weekly holding cost for each item. Find the most economical quantity of 10-speed bicycles to order if it costs the store $\ 20$ to place an order, $\ 5$ to hold a bicycle for a week, and the store expects to sell 40 bicycles/week.