In the following problem, check that it is appropriate to employ the normal approximation to the binomial. Then employ the normal distribution to determine the requested probabilities.
More than the decade ago, high levels of lead in the blood put 85% of children at risk. A concerted effort was made to remove lead from the environment. Now, assume only 15% of children in the United States are at risk of high blood-lead levels.
(a) In random sample of 184 children taken more than decade ago, determine the probability that 50 or more had high blood-lead levels? (Round your answer to three decimal places.)
(b) In random sample of 184 children taken now, what is the probability that 50 or more have high blood-lead levels? (Round your answer to three decimal places.)