The Gallup poll reported that 45% of Americans have tried marijuana. This was based on a survey of 1021 Americans and had a margin of error of plus or minus 5 percentage points with a 95% level of confidence.

a. State the survey results in confidence interval form and interpret the interval.

b. If the Gallup Poll was to conduct 100 such surveys of 1021 Americans, how many of them would result in confidence intervals that did not include the true population proportion?

c. Suppose a student wrote this interpretation of the interval: “We are 95% confident that the percentage of Americans who have tried marijuana is between 40% and 50%.” What, if anything, is incorrect in this interpretation?