We have given the value obtained for the test statistic, z, in a one-mean z-test. We have also specified whether the test is two-tailed, left-tailed, or right-tailed. Determine the P-value in each case and decide whether, at the 5% significance level, the data provide sufficient evidence to reject the null hypothesis in favor of the alternative hypothesis.

Left-tailed test:

a. z = −1.84 

b. z = 1.25