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 standard deviation 36 years. The distribution of dates was more or less normal. What percentage of the dates will be between 1200 and 1300? Estimate a range of years that the upper 20% of the data will be found. Estimate a range of years that the lower 10% of the data will be found. Estimate a range of years centered about the mean in which about 80% of the data will be found.