Jamie, a recruiter, claims that her recruits' entrance exam score is less than 168 points, on average. Several of her coworkers do not believe her, so she decides to do a hypothesis test, at a 1% significance level, to persuade them. She records the scores from 17 recruits. The mean score of the sample recruits is 155 points. Jamie knows from experience that the standard deviation for her recruits' entrance exam score is 19 points. H0: μ≥168; Ha: μ<168
α=0.01 (significance level)
What is the test statistic (z-score) of this one-mean hypothesis test?