A design engineer wants to construct a sample mean chart for controlling the service life of a halogen headlamp his company produces. She knows that this service life is normally distributed with a means of 500 hours and a standard deviation of 20 hours. On three recent production batches, she tested service life on random samples of four headlamps, with these results: Sample SERVICE LIFE (hours) 1 495 500 505 500 2 525 515 505 515 3 470 480 460 470 If she uses upper and lower control limits of 520 and 480 hours, compute the average of each sample to determine if the process is in control no, because sample 3 is outside of the limits Ono, because sample 1 is outside of the limits O yes, process is in control I cannot determine with provided information