The table below shows the average diameter of a pupil in a person’s
eye as he or she grows older.
Age Average Pupil
(years) Diameter (mm)
20 4.7
30 4.3
40 3.9
50 3.5
60 3.1
70 2.7
80 2.3
What is the average rate of change, in millimeters per year, of a
person’s pupil diameter from age 20 to age 80?
(1) 2.4 (3) -2.4
(2) 0.04 (4) -0.04