A design engineer wants to construct a sample mean chart for controlling the service life of a halogen headlamp his company prod
uces. He knows from numerous previous samples that when this service life is in control it is normally distributed with a mean of 500 hours and a standard deviation of 20 hours. On three recent production batches, he tested service life on random samples of four headlamps, with the results?
In the given sample if sample 3 is difficult to control .Because engineer wants to construct a sample mean controlling the service to his company produces.In sample set first two sets have continuous four headlamps but in third it is difficult to handle the control.
