A line of best fit is f(x) ≈ −0.86x + 13.5 for the set of points in the table. A 2-column table with 7 rows. The first column is labeled x with entries 2, 3, 5, 6, 7, 8, 9. The second column is labeled f(x) with entries 12, 10, 10, 8, 9, 5, 6.

Using the equation for the line of best fit, what is a good approximation for the value of the function, f(x), when x = 18?

−5
−2
3
12

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.