# Question

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.

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.

## Answer to relevant Questions

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