In 2017, the entire fleet of light‑duty vehicles sold in the United States by each manufacturer must emit an average of no more than 92 milligrams per mile (mg/mi) of nitrogen oxides (NOX) and nonmethane organic gas (NMOG) over the useful life (150,000 miles of driving) of the vehicle. NOX ++ NMOG emissions over the useful life for one car model vary Normally with mean 88 mg/mi and standard deviation 4 mg/mi.
(a) What is the probability that a single car of this model emits more than 92 mg/mi of NOX ++ NMOG? (Enter your answer rounded to four decimal places.)
Probability - ?
(b) A company has 16 cars of this model in its fleet. What is the probability that the average NOX ++ NMOG level x¯x¯ of these cars is above 92 mg/mi? (Enter your answer rounded to four decimal places.)
Probability - ?