Three different analytical methods are compared for determining Ca in a biological sample. The laboratory is interested in knowing whether the methods differ. The results shown below represent Ca results in ppm determined by an ion-selective electrode (ISE) method, by EDTA titration, and by atomic absorption spectrometry:

(a) State the null and alternative hypotheses.
(b) Determine whether there are differences in the three methods at the 95% and 99% confidence levels.
(c) If a difference was found at the 95% confidence level, determine which methods differ from each other.

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EDTA Titration Absorption Atomic Repetition No ISE 39.2 32.8 41.8 35.3 33.5 29.9 28.7 21.7 0 39.2 44.0 49.2 35.1 39.7 45.9 4