1. 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 86 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 80 mg/mi and standard deviation 4 mg/mi.

Given population parameters are: Population mean, = ____________

Population standard deviation, = ___________

Value of limit, above which it fails to meet the NOx requirement = _____________

a) Individual car that is at the limit in a population, (x=limit)

z-score =

Draw the standard curve and position this sample on it:

Proportion (probability) of all cars that are at or EXCEED the limit = (Use the Standard Normal Curve ... Table A, Moore inside back cover

b) Sample that is the company car fleet (n = 25) ...for sample mean, x = limit! Standardized score of the sample mean: z-statistic =

What is the probability that the average NOx level of this sample of cars exceeds limit?