The backdrop is taped off into 1212 equal sections for the students to paint. ​

​Mark paints 22 times as much as Jill.
Sam paints 33 times as much as Lou.
Lou paints 11 section less than Mark.
Jill paints \frac{1}{12}
12
1
​
of the backdrop.
​

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.