Consider the following competing hypotheses and accompanying sample data drawn independently from normally distributed populations. (You may find it useful to reference the appropriate table: z table or t table) H₀: _{1 2} 0 H_A: _{1 2} < 0

x11 = 263	x22 = 270
s1 = 33	s2 = 24
n1 = 13	n2 = 13

a-1. Calculate the value of the test statistic under the assumption that the population variances are equal. (Negative value should be indicated by a minus sign. Round final answer to 3 decimal places.) B. Calculate the value of the test statistic under the assumption that the population variances are unknown and are not equal. (Negative value should be indicated by a minus sign. Round final answer to 3 decimal places.)