Answer
$k\gt critical~value$: null hypothesis is not rejected.
There is not enough evidence to conclude that $M\gt50$
Work Step by Step
$H_0:~M=50$ versus $H_1:~M\gt50$
$n=7+12=19$
$Critical~value=5$
(According to table XI, for $n=19$ and $α=0.05$ (one tail))
Right-tailed test:
$k=number~of~minus~signs=7$
Since $k\gt critical~value$, we do not reject the null hypothesis.
