Question: Over several years a foreman kept records of how long it took assembly line workers to assemble a unit. He found that workers required an average time of only 15 minutes and standard deviation of 1.5 minutes of completion. A random sample of 64 workers from night shift was timed. Does a sample mean of 16.4 minutes show sufficient evidence to support the claim that the night-shift workers are slow worker?

Test at 0.025 level of significance.