Your professor has decided that, from now on, students who receive less than a 60 percent grade on any exam will be eligible to go to a review session. If they attend the session, they will receive an extra 10 percent on their grade. You see a problem with this policy, and instead propose to your professor that people who go to the review session should receive 50 percent of the difference between their grade and 60 percent. Explain why this situation represents a trade-off between equity and efficiency.