On each trial of an experiment, a subject is presented with a constant soft noise, which is interrupted at some unpredictable time by a noticeably louder sound. The time it takes for the subject to react to this louder sound is recorded. The following list contains the reaction times (in milliseconds) for the 20 trials of this experiment: 164, 171, 250, 285, 236, 261, 273, 212, 193, 235, 311, 217, 241, 229, 296, 269, 226, 186, 175, 257 Find 20th and 75th percentiles for these reaction times.