1. A poll of 811 adults aged 18 or older asked about purchases that they intended to make for the upcoming holiday season. One of the questions asked about what kind of gift they intended to buy for the person on whom they will spend the most. Clothing was the first choice of 487 people. Give a 99% confidence interval for the proportion of people in this population who intend to buy clothing as their first choice.

2. A software company is planning for an upgrade of their software. You must charge customers $100. Are your customers willing to pay this much? You contact a random sample of 40 customers and find that 11 would pay $100 for the upgrade. Find a 95% confidence interval for the proportion of all of your customers (the population) who would be willing to buy the upgrade for $100.

3. What conditions must be met before constructing a confidence interval for a proportion? Be sure to be specific with regard to whether you use p or p-hat in your check.

4. A Gallup Poll used telephone interviews to survey a sample of 1025 U.S. residents over the age of 18 regarding their use of credit cards. The poll reported that 76% of Americans said that they had at least one credit card. Give the 95% margin of error for this estimate