4) for over 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