Geysers are natural fountains that shoot up into the air, at more or less regular intervals, a column of heated water and steam. Old Faithful is one such geyser and is the most popular attraction of Yellowstone National Park, although it is not the largest or grandest geyser in the park. Old Faithful can vary in height from 100-180 feet with an average near 130-140 feet. Eruptions normally last between 1.5 to 5 minutes. From August 1 to August 15, 1985, Old Faithful was observed and the
waiting times between successive eruptions noted. There were 300 eruptions observed, so 299 waiting times were (in minutes) recorded and those shown in Table 8.1.