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H0: μ > 9.4
Ha: μ < 9.4
The critical value for the 0.05 significance level, with one tail is:
z = -1.645
(from a z table)We'll reject H0 if our test statistic is below that.
z = (x-mu)/(s/sqrt(N))
z = (8.6-9.4)/(0.8/sqrt(20))
z = -4.472
That is below the critical value.
Therefore, we reject H0.
That means that the software package has reduced the time.
Let me know if you have any questions,