A major car manufacturer wants to test a new engine to determine if it meets new air pollution standards. The mean emission, μ,
of all engines of this type must be approximately 20 parts per million of carbon. If it is higher than that, they will have to redesign parts of the engine. Ten engines are manufactured for testing purposes and the emission level of each is determined. Based on data collected over the years from a variety of engines, it seems reasonable to assume that emission levels are roughly Normally distributed with σ = 3 parts per million of carbon. What are the appropriate null and alternative hypotheses?
