For the given data, (a) find the test statistic, (b) find the standardized test statistic, (c) decide whether the standardized test statistic is in the rejection region, and (d) decide whether you should reject or fail to reject the null hypothesis. The samples are random and independent.
Claim: $\mu_1 < \mu_2$, $\alpha = 0.01$. Sample statistics: $\bar{x}_1 = 1215$, $n_1 = 40$, $\bar{x}_2 = 1195$, and $n_2 = 60$. Population parameters: $\sigma_1 = 75$ and $\sigma_2 = 110$
(a) The test statistic for $\mu_1 - \mu_2$ is