Which country has the largest real GDP?

Sanjay has an ATV that he values at $3,000. Marilu is looking for a similar ATV but will only pay up to $2,400

Will trade between these two occur? Is there a policy government could implement that would encourage a trade to occur between Sanjay and Marilu? If so, what is that policy and will the policy make society richer?

When Keisha receives a flu vaccination, the additional benefit enjoyed by Keisha's friends is the

A) marginal private benefit. B) marginal external benefit. C) marginal social benefit. D) private benefit. E) marginal private cost.