This is a 2 part question

Use the table below to answer the next question. DPMO stands for Defects Per Million Opportunities. to DPMO 3 2700 4 63 5 .57 6 .002 A product delivery service company claiming 2.1 million consecutive on-time deliveries is performing at: a. less than 3 sigma. b. between 3 and 4 sigma. c. between 4 and 5 sigma. O d. between 5 and 6 sigma. O e. better than or equal to 6 sigma. Which statement(s) is (are) true? a. Queues can appear and disappear abruptly, and can defy logic. O b. It is good practice for a manager (who is supervising queues) to focus on the psychology of customers in the queue (e.g., keeping customers in the queue 'occupied or engaged' and/or informing customers about their expected wait time). c. Mathematical formulae help managers in predicting the number of employees required to provide reasonable service level to keep the customers happy. d. All of the above (i.e., a, b, and care true)