Suppose we have independent random samples of size n 1 = 420 and n2 = 510. The
proportions of success in the two samples are p1= .38 and p2 = .43. Find the 99%
confidence interval for the difference in the two population proportions.
Answer the following questions:
1. Multiple choice: Which equation would you use to solve this problem?
A.
B.
C.
D.
2. List the values you would insert into that equation.
3. State the final answer to the problem
From table 6.1, we see that 99% confidence corresponds to z=2.58. Notice
that the sample sizes are each greater than 30, so we may use eqn. 8.2:
, Answer: B.
So, the interval is (.-0.1333, -0.03326).