January 2017
Beginner
882 pages
203h 41m
English
11. False. If the costs move simultaneously, they should be treated as dependent random variables.
13. False. The mean and variance match, but this is not enough to imply that all of the probabilities match and that p(x) = p(y).
15. False. This implies that X and Y have no covariance, but they need not be independent.
17. True
19. False. The SD of the total is sqrt(2) times σ. The variance of the total sales is 2 times σ2.
21. False. If the effect were simply to introduce dependence (but not otherwise alter the means and SDs), then the expected difference would remain zero.