Let us say that there is a class in which a weekly exam is given. The class has one genius, who always scores $100 \%$, and 19 "regular" students, who always score $85 \%$. The teacher grades the exam on a curve by taking the difference between the highest score and 100 and adding the result to each student's score. For example, if the highest score is 78 , each student will have 22 points added to his or her score. The parents of these students pay them \$1 for each point scored on the exam.
a) Does the genius impose externalities on the rest of the class? If so, what is the value of the marginal externality for each exam?
b) What is the Pareto-optimal configuration of grades?
c) If the highest scoring student on each exam could be taxed for each point he or she scores above the second-highest scoring student, what marginal tax would result in the Pareto-optimal distribution of grades?
d) If the 19 "regular" students were to bribe the genius to start scoring 85 instead of 100 , what is the maximum amount of money they could offer?