A local automotive service center claims it can change the oil in your car in 30 minutes or less. A random sample of their customers produces a sample size of 10, with sample mean 31 minutes and sample standard deviation 1.25 minutes. Suppose that mu is the true mean time for an oil change at this service center. We want to test if the true mean is greater than 30 minutes. Use significance level 0.05.

Question a): What is the standardized value of the test statistic?

Question b): Complete this sentence: At significance level 0.05, we reject H0 if ________. Choices are:

a) |t| >= 1.96

b) |t| >= 2.052

c) t >= 2.080

d) t >= 1.833