A company manufacturing CDs is working on a new technology. A random sample of 788 Internet users were asked: "As you may know, some CDs are being manufactured so that you can only make one copy of the CD after you purchase it. Would you buy a CD with this technology, or would you refuse to buy it even if it was one you would normally buy?" Of these users, 56% responded that they would buy the CD. Complete parts a and b below.

a) Find the 99% confidence interval for this percentage. b) If the company wants to cut the margin of error in half, how many users must they survey?

Please show all work especially for part a) to help me understand better. Thank you