For two individuals who engage in the same two productive activities, it is impossible for one of the two individuals to a. have a comparative advantage in both activities. b. have an absolute advantage in both activities. c. be more productive per unit of time in both activities. d. gain from trade with each other.

How much time on average do americans currently spend watching tv and videos per day?

Imperial crisis inflation invasion pax romana great schismtrade during the , roman generals warred over succession. these conflicts drew soldiers away from the frontier and made the empire vulnerable to

It is widely assumed that people need to engage in intellectual activities such as solving crossword puzzles or mathematics problems in order to maintain mental sharpness as they age. in fact, however, simply talking to other people—that is, participating in social interaction, which engages many mental and perceptual skills—suffices. evidence to this effect comes from a study showing that the more social contact people report, the better their mental skills. which of the following, if true, most seriously weakens the force of the evidence cited? (a) as people grow older, they are often advised to keep exercising their physical and mental capacities in order to maintain or improve them. (b) many medical conditions and treatments that adversely affect a person's mental sharpness also tend to increase that person's social isolation. (c) many people are proficient both in social interactions and in solving mathematical problems. (d) the study did not itself collect data but analyzed data bearing on the issue from prior studies. (e) the tasks evaluating mental sharpness for which data were compiled by the study were more akin to mathematics problems than to conversation.