A car manufacturer wants to test a new engine to determine whether it meets new air-pollution standards. The mean emission,u, of all engines of this type must be less than 21 parts per million of carbon.
A sample of 36 engines are tested for the purposes and emission level of each is determined. The data show the following. Sample mean = 19 standard deviation = 4
Do the data supply sufficient evidence to allow the manufacturer to conclude that this type of engines meet the pollution standard? the manufacturer is willing to risk a Type I error with probability a=0/05