Producer surplus for a particular unit of a good is the price the seller receives for that unit minus the largest amount the seller would accept for it

Are black markets for foreign currencies more likely to occur in countries with an overvalued currency or with an undervalued currency? Why?

What will be an ideal response?

Barter requires a double coincidence of wants. This means that:

a. at least two traders must demand a commodity. b. any two traders involved in a transaction must have money. c. each trader must demand at least two commodities. d. either of the two traders involved in a transaction must have money. e. when two traders are involved in a transaction each trader must want what the other has to offer.