Discussion:
Q: The mean construction time for a standard two-car garage by Arrowhead Construction Company is 3.5 days. The time for the construction process follows the normal distribution. The construction process is modified through the use of "precut and asembled roof trusses" rather than onsite construction of roof rafters. This should shorten the construction time. A sample of 15 garages had a mean time of 3.40 days with a standard desviation of 0.8 days. Does use of the "precut and assembled roof trusses" decrease the construction time? Follow the five-step hyphotesis testing procedure using the 0.05 significance level.