Chapter 8, Problem 8.11P

$\boxed{CJ}$ About half of the police officers in Shinbone, Kansas, have completed a special course in investigative procedures. Has the course increased their efficiency in clearing crimes by arrest? The proportions of cases cleared by arrest for samples of trained and untrained officers are reported here.

Sample 1 (Trained)	Sample 2 (Untrained)
$P_{s1}=0.47$	$P_{s2}=0.43$
$N_1=157$	$N_2=113$