Consider two populations for which m1 30, s1 5 2, m2 5 25, and s2 5 3. Suppose that two independent random samples of sizes n1 5 40 and n2 5 50 are selected. Describe the approximate sampling distribution of x1 2 x2 (center, spread, and shape).

Element x decays radioactively with a half life of 8 minutes. if there are 450 grams of element x, how long, to the nearest tenth of a minute, would it take the element to decay to 37 grams?

X+ y = 5 ; x - y =3 solve using linear combination

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.