One method of calculating the approximate age, in years, of a tree of a particular species is to multiply the diameter of the tree, in inches, by a constant called the growth factor for that species. The table below gives the growth factors for eight species of trees.
| Species of tree | Growth factor |
|---|---|
| Red maple | 4.5 |
| River birch | 3.5 |
| Cottonwood | 2.0 |
| Black walnut | 4.5 |
| White birch | 5.0 |
| American elm | 4.0 |
| Pin oak | 3.0 |
| Shagbark hickory | 7.5 |
A River birch tree and a Black walnut tree both have a current diameter of 10 inches. If both trees continue to grow at their species' typical rates, which of the following is closest to the absolute difference, in inches, in the increase of their diameters over the next 5 years?
0.2
0.3
0.4
0.5
