Use the following information to answer Question20toQuestion21:Apoll was taken every month on how voters will vote on the next federal election. Here are the results of the poll:

Sample Size Liberal Voters

This Month 550 275

Last Month 700 406

20.(4 points) Develop a 95% con dence interval estimate for the di erence between the proportions of voters who will vote for the Liberals in the two populations. Show your calculations.

21.(2 points) From the con dence interval obtained in the previous problem, is there con-

clusive evidence that one of the proportions is signi cantly di erent from the other?