The recipe for producing a high-quality cement specifies that the required percentage of SiO2 is 6.2%. A quality control engineer evaluates this specification weekly by randomly selecting samples from n 5 20 batches on a daily basis. On a given day, she obtained the following values:

a. Estimate the mean percentage of SiO2 using a 95% confidence interval.
b. Evaluate whether the percentage of SiO2 is different from the value specified in the recipe using an α = .05 test of hypotheses.
c. Produce a plot to determine if the procedures you used in parts (a) and (b) were valid.

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L70 9.86 544 428 4.59 8.76 9.16 628 3.83 3.17 5.98 2.77 359 3.17 8.46 7.76 5.55 5. 956 358