Math Problem Statement

In​ 2007, a country had a population of 82 comma 700 thousand. At that​ time, the​ country's population was declining at a rate of 0.032​% per year. If this​ continues, how long will it take the​ country's population to reach​ 82,000 thousand? Use y equals y 0 e Superscript negative 0.00032 t. Question content area bottom Part 1 It will take approximately    enter your response here years.

Solution

To solve this, let's use the exponential decay formula:

y=y0ekty = y_0 e^{-kt}

where:

  • y0=82,700y_0 = 82,700 thousand (the initial population),
  • y=82,000y = 82,000 thousand (the target population),
  • k=0.00032k = 0.00032 (the decay rate),
  • tt is the time in years we are trying to find.

Let's start by rearranging the formula to solve for tt:

  1. Substitute the values into the formula:

    82,000=82,700e0.00032t82,000 = 82,700 e^{-0.00032t}

  2. Divide both sides by 82,700 to isolate the exponential term:

    82,00082,700=e0.00032t\frac{82,000}{82,700} = e^{-0.00032t}

  3. Calculate the left side:

    82,00082,7000.9915\frac{82,000}{82,700} \approx 0.9915

  4. Now, take the natural logarithm of both sides to solve for tt:

    ln(0.9915)=0.00032t\ln(0.9915) = -0.00032t

  5. Calculate ln(0.9915)\ln(0.9915):

    ln(0.9915)0.0085\ln(0.9915) \approx -0.0085

  6. Now, divide by 0.00032-0.00032 to find tt:

    t=0.00850.0003226.56t = \frac{-0.0085}{-0.00032} \approx 26.56

So, it will take approximately 26.56 years for the population to reach 82,000 thousand.

Would you like a more detailed explanation, or do you have any questions?


Related Questions

  1. How would the time change if the decay rate was 0.05% instead of 0.032%?
  2. What is the population after 10 years with the same decay rate?
  3. If the population started at 100,000 thousand, how long would it take to reach 82,000 thousand?
  4. How would the equation change if the population was increasing instead of decreasing?
  5. What is the half-life of this population decline at a rate of 0.032% per year?

Tip

Remember, when solving for tt in exponential decay, taking the natural logarithm is essential to isolate the variable in the exponent.

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Math Problem Analysis

Mathematical Concepts

Exponential Decay
Logarithms

Formulas

Exponential decay formula: y = y₀ e^(-kt)
Natural logarithm to solve for time

Theorems

Properties of Exponential Functions
Logarithmic Properties

Suitable Grade Level

Grades 10-12