The table below shows the average diameter of a pupil in a person's eye as he or she gets older.

age (years). Average Pupil 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 80?

6 answers

How do you think you can solve this problem?
add all the diameters divided by the sum of the ages?
Nope. The question asks for the rate of change. Note that the diameter decreased 0.4 mm every 10 years.

6 * 0.4 = _______ mm

Divide the product by 60 to find the average change per year.
Where did you get 6 from?
There are six decades listed; six changes in diameter.
ANSWER: D: -0.04

Explanation: Average rate of change is the same as slope

2.3 - 4.7/80 - 20 = -2.4/60 = -0.04