At Burnt Mesa Pueblo, archaeological studies have used the method of tree-ring dating in an effort to determine when prehistoric people lived in the pueblo. Wood from several excavations gave a mean of (year) 1243 with a standard deviation of 36 years (Bandelier Archaeological Excavation Project: Summer 1989 Excavations at Burnt Mesa Pueblo, edited by Kohler, Washington State University Department of Anthropology). The distribution of dates was more or less mound-shaped and symmetrical about the mean. Use the empirical rule to:
(a) Estimate a range of years centered about the mean in which about 68% of the data (tree-ring dates) will be found.
(b) Estimate a range of years centered about the mean in which about 95% of the data (tree-ring dates) will be found.
(c) Estimate a range of years centered about the mean in which almost all the data (tree-ring dates) will be found.