Answer: $0.3 per lb per year.
Explanation:
We know that the rate of change in price is given by :-

Given: The price of apples went from $1.99 per lb to $3.19 per lb in four years.
Change in price =

Time = 4 years
Now, the rate of change of the price of apples is given by :-

Hence, the rate of change of the price of apples= $0.3 per lb per year.