A paired data table tracks germinated seed count before and after seed scarification. The values are tray 1: before 11, after 19; tray 2: before 13, after 22; tray 3: before 12, after 20; tray 4: before 10, after 21 seeds/tray. Which calculation correctly determines and interprets the mean change per tray? Round to the nearest hundredth when needed.