Skylar Diggins is reviewing the performance of four call centers under her management. Twelve observations of the amount of time it took to process refund requests have been collected from each of the four call centers. Based on these observations, the following column chart displays the average service time of each call center. Average Time to Process Refund Requests Processing Time (minutes) 35 30 15 10 33 225050 0- A B C D Call Center