Bill used candle molds, as shown, to make candles that were perfect cylinders and spheres: What is the approximate difference in the amount of wax needed to make a candle from each of these molds? (Use π = 3.14.)

21.0 cubic inches
28.26 cubic inches
52.55 cubic inches
66.0 cubic inches

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.