Federal Express offers two kinds of overnight delivery. There is priority overnight, which is guaranteed to reach its destination by 10:30 A.M. the next day, and standard overnight, which is guaranteed to be delivered by 3 P.M. the next day. Priority costs 20% more than standard. Federal Express will often make 2 delivery trips to the same office in the same day just to avoid delivering the standard overnight packages before 10:30 A.M.. This is standard practice even if the package is available to be delivered before 10:30 A.M.. How can you explain this behavior? Hint: Is this a special pricing structure being used?