Consider a market in which there are many potential buyers and sellers of used cars. Each potential seller has one car, which is either of high quality (a plum) or low quality (a lemon). A seller with a low-quality car is willing to sell it for $3,500, whereas a seller with a high-quality car is willing to sell it for $9,000. A buyer is willing to pay $4,500 for a low-quality car and $11,000 for a high-quality car. Of course, only the seller knows whether a car is of high or low quality.
Imagine that 75% of sellers have low quality cars. Assume buyers know that 75% of sellers have low quality cars but are unable to determine the quality of individual cars.
If all sellers offer their cars for sale and buyers have no way of determining whether a car is a high-quality plum or a low-quality lemon, the expected value of a car to a buyer is $ . (Hint: The expected value of a car is the sum of the probability of getting a low-quality car multiplied by the value of a low-quality car and the probability of getting a high-quality car multiplied by the value of a high-quality car.)
Imagine buyers are willing to pay up to the expected value of a car that you found in the previous question.
Since sellers of low-quality cars are willing to sell for $3,500, while sellers of high-quality cars are willing to sell for $9,000, ANSWER (only high-quality sellers, only low-quality sellers, both high-quality and low-quality sellers, neither high-quality and low-quality sellers) will be willing to participate in this market at that price.
The dilemma in this problem is an example of ANSWER (adverse selection, moral hazard, screening, signalling)