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1) The percent composition by mass of sodium bicarbonate in an unknown sample is determined by titration. Eight independent trials give the following percent compositions: 36.59, 43.88, 36.80, 38.30, 37.23,

38.54, 37.90 and 37.57. a. Compute the mean, standard deviation (SD), standard error of the mean(SEM), and 95% probability limit (95% CI) for this set of data. b. Apply the Q test to see which data point may be discarded, then repeat the statistical analysis as for part a. c. Comparing the results before and after the Q test: How much as the mean changed (as a percent of the original mean)? How much as the 95% CI changed (as a percent of the original CI)? Explain how these changes are significant. NOTE: Excel contains built-in functions to compute each of these quantities (see supporting handout). You are encouraged to use Excel for this purpose.

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