Consider testing H0: mu >= 120 vs. H1: mu < 120 based on a random sample of size n = 140 from a population having known population standard deviation sigma = 6.5. At the alpha = 0.10 level of significance, this test would reject the null hypothesis if the calculated z-statistic is: Solution At the alpha = 0.10 level of significance, this test would reject the null hypothesis if the calculated z-statistic is less than -1.28.