1. A study of commuting times reports the travel times to work of a random sample of 18 employed adults in New York State. The mean is x= 25.46 minutes and the standard deviation is s = 20.8 minutes.
What is the standard error (±0.0001) of the mean? ______
2. You are testing H0: ? = 10 against Ha: ? < 10 based on an SRS of 23 observations from a Normal population. The t statistic is -2.
The degrees of freedom for this statistic are _____