with explaination please

Short case Delivery Control at Aramex UAE aramex delivery unlimited Aramex UAE Company deals with thousands of operations and transactions every week. One of its measures of the quality of service it gives its customers is the dependability with which it mails customers' parcels. The quality standard it sets itself is that parcels should be delivered within two days of the 'nominal delivery date' which is specified to the customer. Every week the company samples 1,000 customer deliveries and records the percentage which was not delivered within the standard time. When the process is working normally, only 2 per cent of deliveries are occurred outside the specified period. 1- What will be the upper and lower control limits for the delivery process 2- Discuss the assignable causes for an out of control delivery process