To know the data, count the numbers which has dots above it.
Data = {28, 30, 31, 31, 33, 33, 33, 33, 34, 34, 34, 35, 36, 40}
total number = 14
Mean = (28 + 30 + 31 + 31 + 33 + 33 + 33 + 33 + 34 + 34 + 34 + 35 + 36 + 40)/(14)
Mean = 465/14
Mean = 33.2143