L8_CHEM480_JCCYu

# L8_CHEM480_JCCYu - Percentage of cocaine in a white powder...

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1 Percentage of cocaine in a white powder t test: we want to compare one set of measurements with another to decide whether or not they are “the same”. ± Case 1. We measure a quantity several times, obtaining an average value and a standard deviation. We need to compare our answer with a known, accepted answer. The average does not agree exactly with the accepted answer. Does our measured answer agree or disagree with the known answer “within experimental error”? (Standard reference material) ± Case 2. We measure a quantity multiple times by two different methods that give two different answers, each with its own standard deviation. Do the two results agree with each other standard deviation. Do the two results agree with each other “within experimental error,” or do they disagree? (different methods) ± Case 3. Sample 1 is measured once by method A and once by method B, which do not give exactly the same result. Then a different sample, designated 2, is also measured once by method A and once by method B; and, again, the results are not exactly equal to each other. The procedure is repeated for

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L8_CHEM480_JCCYu - Percentage of cocaine in a white powder...

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