In the United States, paper currency often comes into contact with cocaine either directly, during drug deals or usage, or in counting machines where it wears off from one bill to another. A forensic survey collected fifty $1 bills and measured the cocaine content of the bills. Forty-six of the bills had measurable amounts of cocaine on them (Jenkins 2001). Assume that the sample of bills was a random sample.

a. From these data, what is the best estimate of the proportion of U.S. $1 bills that have a measurable cocaine content?

b. What is a 95% confidence interval for the estimate in part (a)?

c. What is the correct interpretation of your 95% confidence interval?