For more than 20 years, the Occupational Safety & Health Administration has required companies that handle hazardous chemicals to complete material safety data sheets (MSDSs). These MSDSs have been criticized for being too hard to understand and complete by workers. Although improvements were implemented in 1990, a more recent study of 150 MSDSs revealed that only 11% were satisfactorily completed (Chemical & Engineering News, Feb. 7, 2005).
a. Give a point estimate of p, the true proportion of MSDSs that are satisfactorily completed.
b. Find a 95% confidence interval for p.
c. Give a practical interpretation of the interval, part b.