In: Statistics and Probability
The composition of the earth’s atmosphere may have changed over
time. One attempt to discover the nature of the atmosphere long ago
studies the gas trapped in bubbles inside ancient amber. Amber is
tree resin that has hardened and been trapped in rocks. The gas in
bubbles within amber should be a sample of the atmosphere at the
time the amber was formed. Measurement on specimens of amber from
the late Cretaceous era (75 to 95 million years ago) gives these
percents of nitrogen:
63.4 65.0 64.4 63.3 54.8 64.5 60.8 49.1 51.0
These values are quite different from the present 78.1% of nitrogen
in the atmosphere today, but are these differences significant?
Assume (this is not yet agreed on by experts) that these
observations are an SRS from the Cretaceous atmosphere and the
distribution of gas with an approximately normal
distribution.
1. Describe the population of interest and the parameter you want
to draw conclusions about.
2. Graph the data and comment on skewness and outliers. Can the t
procedures be used in this situation?
3. What is the critical t-value for a 95% confidence interval? What
are the degrees of freedom that you used to find the t-value.
4. Construct a 95% confidence interval gfotr the mean percent of
nitrogen in ancient age.
5. Interpret this confidence interval