Conduct a one-tailed hypothesis test given the information below.
A certain brand of fluorescent light tube was advertised as having an average illumination life-span of 2,000 hours. A random sample of 64 bulbs burned out with a mean life-span of 1,970 hours and a sample standard deviation of 80 hours. With a 0.05 level of significance, is the sample mean less than the advertised mean?
A one-tailed hypothesis test is conducted to determine the mean life-span of fluorescent light tubes. From this, it is determined if the average is lower than the advertised mean.