suppose we have a dataset of daily sales for a retail store over the past 30 days (open sheet z score) 144 126 140 188 76 180 158 112 173 126 12 94 94 35 92 34 55 34 183 88 13 44 44 78 61 186 194 117 17 19 . identify any days where the sales revenue is significantly different from the other days, which indicate anomaly or outlier.