Stats Help Needed

#1
I've been going crazy with this problem, and I'm not sure if my solution for it is correct.. please help

In a survey of 10,572 college students, 2358 said they had smoked in the last 30 days. In another survey of 8551 college students taken four years later, 2437 said they had smoked in the last 30 days. At x=10%, can you reject the claim that the proportion of college students who said they had smoked in the last 30 days has not changed?
 

JohnM

TS Contributor
#2
Determine the two proportions:

p1 = 2358/10572

p2 = 2437/8551

Then test:

Ho: p1 = p2 (or p1-p2=0)
Ha: p1<>p2 (or p1-p2<>0)

set alpha=.10

Since the sample sizes are quite large, the proportions can be assumed to follow a normal distribution.

Find z and then determine its probability:

z = (p1-p2)/sp


where sp = sqrt( pq * [(1/n1)+(1/n2)] )
in sp, p must be pooled from p1 and p2 --> p = (x1 + x2)/(n1+n2)
then q = 1-p