The geyser Old Faithful in Yellowstone National Park alternates periods of eruption, which typically last from 1.5 to 4 minutes, with periods of dormancy, which are considerably longer. The following table presents the durations, in minutes, of 30 dormancy periods that occurred during a recent year. 91 99 99 83 99 86 90 96 88 93 88 86 92 116 59 101 90 71 103 97 82 91 89 89 61 96 66 105 90 90 Send data to Excel