Answer
$r\leq lower~critical~value$: null hypothesis is rejected.
There is enough evidence to conclude that the way that the filling machine over- or underfills is not random.
Work Step by Step
$H_0:~The~sequence~is~random$ versus $H_1:~The~sequence~is~not~random$
$n=18$, $n_A=15$, $n_R=3$ and $r=3$
Small sample case:
$lower~critical~value=3$
$upper~critical~value=8$
(According to table X, for $n_1=15$, $n_2=3$)
Test statistic: $r=3$
Since $r\leq lower~critical~value$, we reject the null hypothesis.
