There is a data set consisting of the aluminum contents of 26 bihourly samples of recycled PET plastic from a recycling facility. Those 26 measurements have y(bar)= 142.7 ppm and s= 98.2 ppm. Use these facts to respond to the following. (Assume that n=26 is large enough to permit the use of large-sample formulas in this case.)
a) Make a 90% two-sided confidence interval for the mean aluminum content of such specimens over the 52-hour study period.
b) Make a 95% two-sided confidence interval for the mean aluminum content of such specimens over the 52-hour study period. How does this compare to the answer in part a.
c) Interpret your interval from (a) for someone with little statistical background.