A poll finds that 54% of the population approves of the job that the President is doing;

Question:

A poll finds that 54% of the population approves of the job that the President is doing; the poll has a margin of error of 4% (assuming a 95% degree of confidence).
a. What is the 95% confidence interval for the true population percentage that approves of the President's performance?
b. What was the size of the sample for this poll?