The following table illustrates the points a student can earn on examinations in economics and biology if the student uses all available hours for study.
Economics Biology
100 40
90 50
80 60
70 70
60 80
50 90
40 100
(a) what is the opportunity cost to this student of allocating enough additional study time on economics to move her grade up from a 90 to a 100?
(b) draw a production possibilities curve showing the opportunity cost.