Answer
$t_0\gt t_α$: null hypothesis is rejected.
There is enough evidence to conclude that the ramp meters are effective in maintaining a higher speed on the freeway.
Work Step by Step
$x ̅_1,n_1~and~s_1$ refer to ramp meters on and $x ̅_2,n_2~and~s_2$ refer to ramp meters off.
$x ̅_1=\frac{∑x_{1_i}}{n_1}=40.667$
$s_1=\sqrt {\frac{∑(x_{1_i}-x ̅_1)^2}{n_1}}=10.040$
$x ̅_2=\frac{∑x_{2_i}}{n_2}=34.533$
$s_2=\sqrt {\frac{∑(x_{2_i}-x ̅_2)^2}{n_2}}=9.561$
$H_0:~µ_1=µ_2$ versus $H_1:~µ_1\gt µ_2$
$t_0=\frac{(x ̅_1-x ̅_2)-(µ_1-µ_2)}{\sqrt {\frac{s^2_1}{n_1}+\frac{s^2_2}{n_2}}}=\frac{(40.667-34.533)-0}{\sqrt {\frac{10.040^2}{15}+\frac{9.561^2}{15}}}=1.714$
$n=15$, so:
$d.f.=n-1=14$
Left-tailed test:
$t_α=t_{0.10}=1.345$
(According to Table VI, for d.f. = 14 and area in right tail = 0.10)
Since $t_0\gt t_α$, we reject the null hypothesis.
