A tree is at present 9 feet tall. If every year it grows $$\frac{1}{9}$$th of its height. What will be the height of the tree after three years?

Correct option is B

Given:
Initial height of the tree = 9 feet
Annual growth rate = 1/9 th of current height per year
Time = 3 years

Formula:

$$\text{Future Height} = \text{Initial Height} \times \left(1 + r\right)^t$$

​Solution:

$$\text{Initial Height} = 9 \text{ feet} \\\text{Growth rate per year} = \frac{1}{9} \\\text{Time} = 3 \text{ years} \\[10pt]\text{Future Height} = 9 \times \left(1 + \frac{1}{9} \right)^3 \\= 9 \times \left(\frac{10}{9} \right)^3 \\\ \\= 9 \times \frac{1000}{729} \\\ \\= \frac{9000}{729} \approx 12.34 \text{ feet}$$​