A study by Careerbuilder.com found that 20% of companies check out job candidates' profiles on social networking sites like Facebook and MySpace before deciding whether to employ them. Assuming that the survey included a simple random sample of 1200 companies, construct a 90% confidence interval for 7T 5 the population proportion of companies that check social-networking sites before offering employment.
Source: Carrie-Ann Skinner, "Employers Admit Checking Facebook Before Hiring," pcworld.com, September 14, 2008.