Shift 2: 18 25 56 42 29 38 54 47 35 30. shift 2: 23 19 50 49 67 34 30 59 40 33. shift 3: 19 22 24 40 45 29 33 29 39 59. shift 4: 21 23 25 40 35 19 70 40 22 23.    the summary statistics for all of the workers at a steel factory are shown. four sample groups were taken from each of the four shifts. for which sample group is the mean closest to the population mean?