Suppose a baker claims that her bread height is less than 15 cm, on average. Several of her customers do not believe her, so the baker decides to do a hypothesis test, at a 5% significance level, to persuade them. She bakes 22 loaves of bread. The mean height of the sample loaves is 13 cm. The baker knows from experience that the standard deviation for her bread height is 1.2 cm. H0: μ≥15; Ha: μ<15 α=0.05 (significance level) What is the test statistic (z-score) of this one-mean hypothesis test, rounded to two decimal places?