In a post office, there are 3 steps that each customer needs to take, in order for his/her/their parcel or order to be received and accepted by the staff for delivery to any destination. The first step is to give the parcel to the operator for weighting, checking the destination (local, national, or oversees), as well as to specify the type of shipment (regular, priority, express, etc) so that a total fee can be calculated by the operator. The 2nd step is for the customer to provide the sender and receivers address on the parcel and/or to fill a form that is provided by the operator. The last step is to have the parcel registered with a tracking number by the operator, and to pay for the fees and get a receipt. This process is shown in the process flow diagram below. Please answer the questions 4-1 to 4-3 according to the information provided on the diagram.

5-1. What is the Flow Time of this process?

5-2. In average, there are 3 customers (parcels) waiting to get their parcel weighted by the operator (step 1), and 2 customers are waiting to pay for their fees (step 3). The operator is constantly busy serving 1 customer (on the steps that need the operator). Also, 2 customers are filling the form in average (at any point in time). Based on this information, what is the total inventory of this process?

5-3. What is the hourly rate of customer (parcel) arrivals in this post office?