Question

A

Answer 1

@mathmate

Answer 2

@satellite73

Answer 3

n1=45, p1=0.75
n2=60, p2=0.55

H0: P1=P2
Ha: P1!=P2
We will use a significant level of 0.10 and a two-tailed test.

Pooled sample proportion
p=(p1*n1+p2*n2)/(n1+n2)=0.6357
Standard error,
SE=sqrt(p*(1-p)*(1/n1+1/n2))=0.09490
Test statistic,
z=(p1-p2)/SE=2.1075
P(Z>z)=1-0.9824=0.0176 < 5% (two tail test)
Therefore there is no enough evidence to support H0, and Ha P1!=P2 will be accepted.

For more examples, see:
http://stattrek.com/hypothesis-test/difference-in-proportions.aspx