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 |
Two trees, a Cottonwood and a Shagbark hickory, currently have the same diameter. Which of the following statements about their approximate ages is true?
The Cottonwood tree is approximately 3 times older than the Shagbark hickory tree.
The Shagbark hickory tree is more than 3 times older than the Cottonwood tree.
The Cottonwood tree is approximately 5.5 years older than the Shagbark hickory tree.
The Shagbark hickory tree is approximately 5.5 years older than the Cottonwood tree.
