Drugs ‘R US operates a mail order pharmaceutical business in San Francisco. The firm receives an average of $325,000 in payments per day. On average, it takes four days from the time customers mail their checks until the firm receives them. The company is considering establishing a lockbox system, in which customers' payments would be sent to nearby banks (local in terms of the purchasers) instead of directly to San Francisco. Banks in the lockbox locations would then wire the daily receipts to a single (concentration) bank