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 m₂= year 1122 with standard deviation σ₂= 40years. Assume thatboth sites had dates that were approximately normally distributed. In the first area, an object was found and dated as x₁= year1250. In the second area,

another object was found and dated as x₂= year 1234.

(a) Convert both x₁ and x₂ to z values, and locate both of these values under the standard normal curve of Figure 6-15.

(b) Interpretation Which of these two items is the more unusual as an archaeological find in its location?

The Standard Normal Distribution    (μ = 0, σ = 1)

Fig 6-15

11/9/2014