Answer
$t_0\lt -t_{\frac{α}{2}}$: null hypothesis is rejected.
There is enough evidence to conclude that $µ_1\ne µ_2$.
Work Step by Step
$H_0:~µ_1=µ_2$ versus $H_1:~µ_1\ne µ_2$
$t_0=\frac{(x ̅_1-x ̅_2)-(µ_1-µ_2)}{\sqrt {\frac{s^2_1}{n_1}+\frac{s^2_2}{n_2}}}=\frac{(111-104)-0}{\sqrt {\frac{8.6^2}{20}+\frac{9.2^2}{20}}}=2.486$
$n=20$, so:
$d.f.=n-1=19$
Two-tailed test:
$t_{\frac{α}{2}}=t_{0.025}=2.093$
(According to Table VI, for d.f. = 19 and area in right tail = 0.025)
Also, $-t_{\frac{α}{2}}=-2.093$
Since $t_0\lt -t_{\frac{α}{2}}$, we reject the null hypothesis.
