More than a decade ago, high levels of lead in the blood put 88% of children at risk. A concerted effort was made to remove lead from the environment. Now, according to the Third National Health and Nutrition Examination Survey (NHANES III), conducted by the Centers for Disease Control and Prevention, only 9% of children in the United States are at risk of high blood lead levels.
(a) In a random sample of 200 children taken more than a decade ago, what is the probability that 50 or more had high blood lead levels?
(b) In a random sample of 200 children taken now, what is the probability that 50 or more have high blood lead levels?