Step 1 :Find the difference of sample means: x_bar1 - x_bar2 = 2.31 - 2.63.
Step 2 :Calculate the standard error: SE = \(\sqrt{\frac{s_1^2}{n_1} + \frac{s_2^2}{n_2}}\).
Step 3 :Calculate the test statistic: z = \(\frac{(x_\text{bar1} - x_\text{bar2}) - 0}{SE}\).