1. As the degrees of freedom become larger, the difference between the t and z distributions becomes
A. narrower
B. stays the same
C. wider
2. Below are normal quantile plots for two data sets. For which set(s) is(are) inference using the t distribution valid?
A.
B. 
C. Both choices are correct.
3. The manager of an automobile dealership is considering a new bonus plan to increase sales. Currently, the mean sales rate per salesperson is five automobiles per month. The correct set of hypotheses to test the effect of the bonus plan is
A. H0: μ = 5, Ha: μ > 5
B. H0: μ > 5, Ha: μ = 5
C. H0: = 5, Ha: > 5