Please help Oak wilt is a fungal disease that infects oak trees. Scientists have discovered that a single tree in a small forest is infected with oak wilt. They determined that they can use this exponential model to predict the number of trees in the forest that will be infected after t years.
f(t) = e^0.4t
1. The scientists believe the forest will be seriously damaged when 21 or more of the forest’s 200 oak trees are infected by oat wilt. According to their model, how many years will it take for 21 of the trees to become infected?

Type the correct answer in the box. Use numerals instead of words. Round your answer to the nearest tenth.

2. Rewrite the exponential model as a logarithmic model that calculates the number of years g (x) for the number of infected trees to reach a value of x.

To solve this question, we need to solve an exponential equation, which we do applying the natural logarithm to both sides of the equation, both to find the needed time and to find the inverse function. From this, we get that:

Number of trees infected after t years:

The number of trees infected after t years is given by:

Question 1:

We have to find the number of years it takes to have 21 trees infected, that is, t for which:

Thus:

To isolate t, we apply the natural logarithm to both sides of the equation, and thus:

Thus, it will take 7.6 years for 21 of the trees to become infected.

Question 2:

We have to find the inverse function, that is, first we exchange y and x, then isolate x. So

Again, we apply the natural logarithm to both sides of the equation, so:

Thus, the logarithmic model is:

For an example of a problem that uses exponential functions and logarithms, you can take a look at

nope.   happens to me as well.

-aparri