Order the data:125, 160, 169, 171, 175, 186, 210, 243, 250, 258, 390, 420Find middle observation:[125, 160, 169, 171, 175, 186] | [210, 243, 250, 258, 390, 420]Median = (186 + 210)/2 = 198Find middle observation of each half:[125, 160, 169 | 171, 175, 186], [210, 243, 250 | 258, 390, 420]Lower quartile = (169 + 171)/2 = 170, Upper quartile = (250 + 258)/2