1.Suppose we want to estimate the proportion of college students who use stimulants to help them study. If we want to estimate this proportion to within 4% at the 95% confidence level, how many randomly selected college students must we survey?

2. P(-2.75 < z < -0.09)

3. A political candidate has asked you to conduct a poll to determine what percentage of people support her. If the candidate only wants a 1.5% margin of error at a 97.5% confidence level, what size of sample is needed?

4. Out of 100 people sampled, 47 had kids. Based on this, construct a 90% confidence interval for the true population proportion of people with kids. Give your answers as decimals, to three places

5. A class is given an exam. The distribution of the scores is normal. The mean score is 74 and the standard deviation is 9. Determine the test score, cc, such that the probability of a student having a score greater than cc is 62%.