Answer:
A) the average value of a used car = ($13,000 + $5,000) / 2 = $18,000 / 2 = $9,000
B) the average value is $4,000 higher than the value of a bad used car. A good used car exceeds the average value by $4,000.
C) No, because he/she knows that his good used car is worth much more.
D) If the seller accepts the average value, it is more likely that his car is a bad car.
E) The majority of used cars should be bad or lemon, since good used cars will be sold quickly. If all good used cars were removed, then the price of used cars would drop to $5,000 (the value of a lemon car).