A random sample of 15 workers from a vacuum flask assembly line was selected from a large number of such workers. Ivor Stopwatch, a work-study engineer, asked each of these workers to assemble a one-liter vacuum flask at their normal working speed. The times are taken, in seconds, to complete these tasks to have a sample mean of 116.1 and the sample standard deviation is 15.5. Assuming that this sample came from an underlying normal population, investigate the claim that the population means assembly time is less than 2 minutes. What does t-test equal to? Two decimal places.
