Answer:
If, however, there are ten goods in a barter economy, then one needs to know: 20 prices in order to exchange one good for another.
(a) 20
Explanation:
A barter economy is a cashless economy where individuals trade goods and services based on negotiated rates. Barter exchange forms one of the earliest forms of exchange where people often exchanged goods and services. People still participate in barter exchange without knowing, an example is an information technology expert providing computer services to a farmer in exchange for a specific quantity of vegetables supply from the farmer. In a barter economy, one needs to know the price of the good or service he/she is offering and the price of the good he/she is getting in return to effectively quantify the goods and services.
For example; when there are five goods in an economy one needs to know ten prices since he/she needs to determine the demand price of that good or service that most consumers are willing to pay and the supply price that most producers are willing to accept as payment for their goods. The customer price forms the lower price limit of the good while the producer's price forms the upper price limit. This can be useful in negotiation. In this way, each good should have two prices attached to it.
In our case;
10 goods=10×2=20 prices
