Chapter 6.2, Problem 12P

Normal Curve: Tree Rings Tree-ring dates were used extensively in archaeological studies at Burnt Mesa Pueblo (Bandelier Archaeological Excavation Project: Summer 1989 Excavations at Burnt Mesa Pueblo, edited by Kohler, Washington State University Department of Anthropology). At one site on the mesa, tree-ring dates (for many samples) gave a mean date of μ₁ = year 1272 with standard deviation σ₁ = 35 years. At a second, removed site, the tree-ring dates gave a mean of μ₂ = year 1122 with standard deviation σ₂ = 40 years. Assume that both sites had dates that were approximately normally distributed. In the first area, an object was found and dated as x₁ = year 1250. In the second area, another object was found and dated as x₂ = year 1234.

1. (a) Convert both x₁ and x₂ to z values, and locate both of these values under the standard normal curve of Figure 6-15.
2. (b) Interpretation Which of these two items is the more unusual as an archaeological find in its location?

FIGURE 6-15

The Standard Normal Distribution

(μ = 0, σ = 1)