Question

18) (6 pts) A study of 40 English composition professors showed that they spent, on average, 12.6 minutes correcting a student's term paper. (a) Find the 90% confident interval of the population mean u when S = 2.5 minutes. (b) If a professor stated that he spent, on average, 30 minutes correcting a term paper, what would be your reaction :)) ? 19) (5 pts) Find the Z-score that corresponds to the given area Shaded Area A-0.8907 20) (6 pts) Box contains 22 calculators, 5 of them might be defective. For a quality assurance 6 will be picked for checked. What the probability to chose 4 defective and 2 good.

Answer 1

(18) n=40 = 1206, 5=2.5 90% confidence interes for en is (āt 1.655X) - (1216 31685x205) =(11.93, 18.24) 140 11093 LMC 13027 b Amrage of 30 minutes à very much far from the upper unit of the confidence Enteral which is not possible. a Ginen P(Z&Z) = 0.8907 » ploctet) = 0.3907 32=(-1.23) 22 9,20,= 22, pcdefect'ie) = 012243 if n=6, PCA defetue 2004) = Sea ( 6 5 = 0.0239 )