NINTH EDITION HAL VARIAN ACADEMIC
REVIEW ANSWERED EXERCISES FULL
SOLUTION 2026
◉ Opportunity cost. Answer: The value of all that must be sacrificed to
do the activity.
◉ Sunk cost. Answer: A cost that cannot be avoided regardless of future
actions.
◉ Reservation price. Answer: The minimum amount you would spend to
do something.
◉ Marginal cost. Answer: The cost of an additional unit.
◉ Marginal benefit. Answer: The benefit of an additional unit.
◉ MB = MC. Answer: Stop when marginal benefit = marginal cost
◉ Price elasticity of demand. Answer: The percentage change in the
quantity of a good demanded that results from a 1 percent change in its
price.
, ◉ Elasticity of demand. Answer: εD = %∆QD / %∆P
Price Elasticity of Demand = % Change in Quantity Demanded / %
Change in Price
◉ Elasticity of supply. Answer: εS = %∆QS / %∆P
◉ Elasticity. Answer: A measure of how much one economic variable
responds to changes in another economic variable.
◉ Elastic. Answer: Less than -1
◉ Unit Elastic. Answer: -1
◉ Inelastic. Answer: Greater than -1
◉ Normal Good. Answer: Income ↑ ⇒ Demand ↑ and Income ↓ ⇒
Demand ↓
◉ Inferior Good. Answer: Income ↑ ⇒ Demand ↓ and Income ↓ ⇒
Demand ↑
◉ Compliments. Answer: Price of one ↑ ⇒ Demand for the other ↓