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The population [tex]\( P \)[/tex] of a city increases according to the equation [tex]\( P = 5000 e^{0.0238 t} \)[/tex], where [tex]\( t \)[/tex] represents the number of years since the city was established.

Part A

Given that the city's population continues to increase at the same rate, what is an equation that represents the number of years, [tex]\( t \)[/tex], it will take for the population to reach 30,000? Express your answer as a logarithm.

Enter your answer in the box.
[tex]\[ t = \boxed{\log \left( \frac{30000}{5000} \right) \big/ 0.0238} \][/tex]

Part B

Approximately how many years will it take for the city's population to reach 30,000? Round your answer to the nearest whole number.

Enter your answer in the box.
[tex]\[ \boxed{73} \][/tex] years


Sagot :

Let's solve this problem step-by-step.

### Part A:

We start with the given population growth formula:
[tex]\[ P = 5000 e^{0.0238 t} \][/tex]

We want to find the number of years [tex]\( t \)[/tex] it will take for the population to reach 30,000. So, we set [tex]\( P = 30000 \)[/tex]:

[tex]\[ 30000 = 5000 e^{0.0238 t} \][/tex]

First, we divide both sides of the equation by 5000 to isolate the exponential term:
[tex]\[ \frac{30000}{5000} = e^{0.0238 t} \][/tex]
[tex]\[ 6 = e^{0.0238 t} \][/tex]

Next, we take the natural logarithm (ln) of both sides to solve for [tex]\( t \)[/tex]:
[tex]\[ \ln(6) = \ln(e^{0.0238 t}) \][/tex]

Using the logarithm property [tex]\( \ln(e^x) = x \)[/tex], we get:
[tex]\[ \ln(6) = 0.0238 t \][/tex]

Finally, we solve for [tex]\( t \)[/tex]:
[tex]\[ t = \frac{\ln(6)}{0.0238} \][/tex]

So the equation that represents the number of years [tex]\( t \)[/tex] is:
[tex]\[ t = \frac{\ln(6)}{0.0238} \][/tex]

### Part B:

To find the approximate number of years, we evaluate the equation [tex]\( t = \frac{\ln(6)}{0.0238} \)[/tex].

The numerical result of this expression is approximately 75 years when rounded to the nearest whole number.

Therefore, it will take approximately:
[tex]\[ 75 \text{ years} \][/tex]
for the city's population to reach 30,000.