a.

Find the average rate of change in the measure over time.

.

Consider the ordered pairs and .

                    (Formula for slope)

          (Substitute and )

                                 (Subtract: and )

                        (Simplify)

So, the average rate of change in the growth of a starfish is per year.

b.

Since the rate of change in the growth of a starfish is per year, the fish will grow in years.

Therefore, the size of the starfish will be in the year .

a. The average rate of change in the growth of a starfish is per year.

b. The starfish will be in the year .