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 σ = 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.
(a) Convert both x1 and x2 to z values, and locate both of these values under the standard normal curve of Figure 7-12.

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

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3 2 2 3 68% of area 95% of area 99.7% of area