A certain brand of fluorescent light tube was advertised as having an effective life span before burning out of 4000 hours. A random sample of 84 bulbs was burned out with a mean illumination life span of 1870 hours with a sample standard deviation of 90 hours. Conduct a one-tailed hypothesis test at alpha=.10 to determine if this sample data provides sufficient evidence to indicate that the bulbs have their advertised life expectancy. Do NOT do a confidence interval.