Answer
(a) $n=21$, $n_y=11$, $n_n=10$ and $r=10$
(b) $lower~critical~value=6$
$upper~critical~value=17$
(c) $lower~critical~value\lt r\lt upper~critical~value$: null hypothesis is not rejected.
There is not enough evidence to conclude that the sequence is not random.
Work Step by Step
(a) $n=21$, $n_y=11$, $n_n=10$ and $r=10$
(b) $lower~critical~value=6$
$upper~critical~value=17$
(According to table X, for $n_1=11$, $n_2=10$)
(c) Small sample case:
$H_0:~The~sequence~is~random$ versus $H_1:~The~sequence~is~not~random$
Test statistic: $r=10$
Since $lower~critical~value\lt r\lt upper~critical~value$, we do not reject the null hypothesis.