Sylvia and Patrick plotted the information they gathered on the weight of cars and the mileage they get. Then they each drew a line on the graph that they felt best fit the data. Sylvia’s line is a line of best fit because her line is close to most of the data points . Patrick’s line is not a line of best fit as his line does not fit the data points exactly .

An automobile assembly line operation has a scheduled mean completion time, μ, of 12 minutes. the standard deviation of completion times is 1.6 minutes. it is claimed that, under new management, the mean completion time has decreased. to test this claim, a random sample of 33 completion times under new management was taken. the sample had a mean of 11.2 minutes. assume that the population is normally distributed. can we support, at the 0.05 level of significance, the claim that the mean completion time has decreased under new management? assume that the standard deviation of completion times has not changed.