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Confidence interval for mean and Box Plot

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Solution Summary

This solution includes a step by step method for computing the given confidence interval and box plot.

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The box Plot suggests that average time to drill under Wet Drilling is less than that of Dry drilling.
b. Hypothesis testing
H0: There is no significant difference in the mean time to drill under both methods.
H1: There is significant difference in the mean time to drill under both methods.
Test Statistic used is independent sample t test. The test statistic used is
where
Significance level = 0.01
Rejection criteria: Reject the null hypothesis, if the calculated value of t is greater than the critical value of t at 0.01 significance level.

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t-Test: Two-Sample Assuming Equal Variances

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