Consider the process of grocery delivery to the customers after online ordering. Please respond the following questions based on the information provided below.
4-1. If the workday is 8 hours, and if it takes 30 minutes to deliver each order, calculate the daily rate of order delivery. Show how you obtained this number
4-2. If orders are received at the grocery store at a rate of 3 per hour, considering that prep for delivery takes 15 minutes, how many orders in average will be awaiting prep at any point in time at this grocery store?