Xochitl planted two saplings in her yard. The maple tree is 2.5 feet tall and will grow at a rate of 17% each year. The oak tree is 5.6 feet tall and grows at a rate of 8% each year. How many years will it take the two trees to reach the same height? (1 point)

Responses

Approximately 10 years
Approximately 10 years

They will never be the same height.
They will never be the same height.

Approximately 34 years
Approximately 34 years

Approximately 2.5 years

1 answer

Let the height of the maple tree after \( t \) years be given by:

\[ M(t) = 2.5(1 + 0.17)^t = 2.5(1.17)^t \]

Let the height of the oak tree after \( t \) years be given by:

\[ O(t) = 5.6(1 + 0.08)^t = 5.6(1.08)^t \]

We need to find when these two heights are equal:

\[ 2.5(1.17)^t = 5.6(1.08)^t \]

Dividing both sides by 2.5 gives:

\[ (1.17)^t = \frac{5.6}{2.5}(1.08)^t \]

Calculating \( \frac{5.6}{2.5} \):

\[ \frac{5.6}{2.5} = 2.24 \]

The equation simplifies to:

\[ (1.17)^t = 2.24(1.08)^t \]

Rearranging gives us:

\[ \frac{(1.17)^t}{(1.08)^t} = 2.24 \]

This can be rewritten as:

\[ \left(\frac{1.17}{1.08}\right)^t = 2.24 \]

Calculating \( \frac{1.17}{1.08} \):

\[ \frac{1.17}{1.08} \approx 1.08333 \]

Now, rewriting the equation gives:

\[ 1.08333^t = 2.24 \]

Taking the logarithm of both sides:

\[ \log(1.08333^t) = \log(2.24) \]

Using the property of logarithms:

\[ t \cdot \log(1.08333) = \log(2.24) \]

Now solving for \( t \):

\[ t = \frac{\log(2.24)}{\log(1.08333)} \]

Calculating the values:

  1. \( \log(2.24) \approx 0.3508 \)
  2. \( \log(1.08333) \approx 0.0357 \)

Thus:

\[ t \approx \frac{0.3508}{0.0357} \approx 9.83 \]

Therefore, it will take approximately 10 years for the two trees to reach the same height. Thus, the correct response is:

Approximately 10 years.