The level of nitrogen oxides NOX in the exhaust of cars of a

The level of nitrogen oxides (NOX) in the exhaust of cars of a particular model varies Normally with mean 0.21 grams per mile (g/mi) and standard deviation 0.051 g/mi. Government regulations call for NOX emissions no higher than 0.27 g/mi.

What is the probability (±0.001) that a single car of this model fails to meet the NOX requirement? __

A company has 10 cars of this model in its fleet. What is the probability (±0.001) that the average NOX level xbar of these cars is above the 0.27 g/mi limit? __

Solution