A company manufacturing CDs is working on a new technology. A random sample of 703 Internet users were asked: "As you may know, some CDs are being manu- factured so that you can only make one copy of the CD af- ter 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, 64% responded that they would buy the CD.
a) Create a 90% confidence interval for this percentage.
b) If the company wants to cut the margin of error in half, how many users must they survey?