19. How does the mean of the sampling distribution based on random samples of size 20 compare to the mean of the sampling distribution based on random samples of size 40?

If you take many samples of 20 and watch its mean, you will find them way more spread than the mean of many samples of 40. This has a reason: the higher the sample length, the less the standard deviation. Also, for the law of big numbers, the mean of the samples of 40 will more likely be closer to the real population mean of the samples of 20.