Question

1. The average time for a plastic bottle to completely degrade in a landfill is reported to be 500 years[1]. Data on estimated time of degradation (in years) were collected from samples subject to respirometry tests[2], and were recorded in ‘prob set 7 data.csv’.
   1. What is the mean value observed for time of degradation?
   2. What is the standard error observed for time of degradation?
   3. Find the 95% confidence intervals for the unknown population mean time of degradation and interpret its meaning.
   4. Test the hypothesis that time of degradation for plastic bottles is more than 500 years, at the a=0.05 level. (Be sure to right down all steps – including hypotheses – as in the lecture notes, and interpret the meaning of the test!)
   5. How would your answer change if you were testing they hypothesis that the time of degradation was different than 500 years?
   6. Another report was released that claimed that the time of degradation for plastic bottles was 555 years. Test the hypothesis that the true mean degradation time is less than this, at the a=0.01 level.

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Answer 1