QUESTION 5 

(a) In the February 20th issue of the East Daily Times, it was reported that n = 418 insured patients were surveyed on their opinions about insurance rates. Of the 418 surveyed, Y = 280 blamed rising insurance rates on large court settlements against doctors. With 95% confidence, estimate 4 the parameter p, that is, the proportion of all insured patients who blame rising insurance rates on large court settlements against doctors. 

(b) A random sample of 126 police officers subjected to constant inhalation of automobile exhaust fumes in downtown Cairo, had an average blood lead level concentration of 29.2 μg/dl. Assume x, the blood lead level of a randomly selected policeman, is normally distributed with a standard deviation of σ = 7.5 μg/dl. Historically, it is known that the average blood lead level concentration of humans with no exposure to automobile exhaust is 18.2 μg/dl. Construct 90% confidence interval estimator for average blood lead level.