2.22 Estimating the age of glacial drifts. Tills are glacial drifts consisting o
ID: 3204245 • Letter: 2
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2.22 Estimating the age of glacial drifts. Tills are glacial drifts consisting of a mixture of clay, sand, gravel, and boulders. Engineers from the University of Washington's Department of Earth and Space Sciences studied the chemical makeup of buried tills in order to estimate the age of the glacial drifts in Wisconsin. (American Journal of Science, Jan. 20 The ratio of the elements aluminum (Al) and beryllium (Be) in sediment is related to the duration of burial. The Al/Be ratios for a sample of 26 buried till specimens are given in the table. With the aid of a graph, estimate the proportion of till specimens with an Al/Be ratio that exceeds 4.5 TILL RATIO 3.75 4.05 3.81 3.23 3.13 3.30 3.21 3.32 4.09 3.90 5.06 3.85 3.88 4.06 4.56 3.60 3.27 4.09 3.38 3.37 2.73 2.95 2.25 2.73 2.55 3.06 Source: Adapted from American Journal of Science, Vol. 305, No. 1 Jan. 2005, p. 16 (Table 2).Explanation / Answer
It's 3.846%
since there is only 1 ratio (4.56) which is >4.5
so, 1/26=3.846%
we can also test for its significant if asked.
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