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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
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.

Respuesta :

To solve this question, we need to solve an exponential equation, which we do applying the natural logarithm to both sides of the equation, getting that it will take 7.6 years for for 21 of the trees to become infected.

Model:

The exponential model for the number of infected trees after t years is given by:

[tex]f(t) = e^{0.4t}[/tex]

How many years will it take for 21 of the trees to become infected?

This is t for which:

[tex]f(t) = 21[/tex]

Thus

[tex]e^{0.4t} = 21[/tex]

Applying the natural logarithm to both sides:

[tex]\ln{e^{0.4t}} = \ln{21}[/tex]

[tex]0.4t = \ln{21}[/tex]

[tex]t = \frac{\ln{21}}{0.4}[/tex]

[tex]t = 7.6[/tex]

It will take 7.6 years for for 21 of the trees to become infected.

For another example of a problem in which an exponential equation is solved, you can check brainly.com/question/24290183.