To find out how fast a tree grows, you can measure its trunk. A giant red oak's diameter was 248 inches in 1965. The tree's diameter had grown to 251 inches in 2005. Find the average rate of change in the diameter of the tree per year.
The answer is 6.25 because you take 251 and divide it by 40 and you will end up with 6.25. The number 40 comes from the years 1965 to 2005. And the you just divide
