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 is the t-test value?
