A psychology researcher wants to evaluate the effect of a clinical treatment on ameliorating depression by lowering depression scores. Suppose the population mean for depression score is μ = 40. She sampled 10 individuals to administer the treatment, and after the treatment, the average depression score for the group is M = 35. Assume the sample variance is 18. Compute a one-tailed hypothesis test at α = 0.05 to determine whether the treatment effect is significant and find the 95% confidence interval for μ.