An engineer wants to know if the mean strengths of three different concrete mix designs differ significantly. He randomly selects nine cylinders that measure 6 inches in diameter and 12 inches in height in which mixture 67-0-301 is poured, nine cylinders of mixture 67-0-400, and nine cylinders of mixture 67-0-353. After 28 days, he measures the strength (in pounds per square inch) of the cylinders. The results are presented in the following table:

(a) State the null and alternative hypotheses.
(b) Explain why we cannot use one-way ANOVA to test these hypotheses.

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Mixture Mixture Mixture 67-0-301 67-0-400 67-0-353 4070 3960 4090 4120 4150 3820 4040 3830 4330 4640 3820 3750 3780 3940 4620 4190 4010 3990 3730 3890 4080 3850 4150 4320 3990 4890 4190