17.13 Diamonds. A group of earth scientists studied the small diamonds found in a nodule of rock carried up to the
earth’s surface in surrounding rock. This is an opportunity to examine a sample from a single population of
diamonds formed in a single event deep in the earth.10 Table 17.3 (page 460) presents data on the nitrogen
content (parts per million) and the abundance of carbon-13 in these diamonds. (Carbon has several isotopes, forms
with different numbers of neutrons in the nuclei of their atoms. Carbon-12 makes up almost 99% of natural carbon.
The abundance of carbon-13 is measured by the ratio of carbon-13 to carbon-12, in parts per thousand more or less
than a standard. The minus signs in the data mean that the ratio is smaller in these diamonds than in standard
carbon.)
We would like to estimate the mean abundance of both nitrogen and carbon-13 in the population of
diamonds represented by this sample. Examine the data for nitrogen. Can we use a t confidence interval for
mean nitrogen? Explain your answer. Give a 95% confidence interval if you think the result can be trusted.
Stem and Leaf -- Selected Field: C14
C14
1 | 2: represents 1.2
leaf unit: 0.1
n: 24
-4
-3
-3
-2
-2
-1
-1
-0
|
|
|
|
|
|
|
|
002
5678889
2
7788
0134
58
13
8
Z Test One-Sample -- Selected Field: C14
Alternative Hypothesis
Two-Sided
Confidence Level
0.9500
Statistic
Result
N
24
Mean
-2.8825
Standard Error
0.2041
z Statistic
-14.1213
p Value
2.8073e-45
CI Upper Bound
-2.4824
CI Lower Bound
-3.2826