In 1970, the population of a small town was 4,200. The population is decreasing at a rate of 2.4% per year. Which of the following shows an exponential decay function to find the quarterly decay rate?The population is decreasing by how much percent per quarter?

In 1970 the population of a small town was 4200 The population is decreasing at a rate of 24 per year Which of the following shows an exponential decay function class=

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Answer:

a. y = 4,200 [tex]0.976^{4t}[/tex]

b. 9.2%

Step-by-step explanation:

Given the information:

  • The intinital value: 4,200
  • The population is decreasing at a rate of 2.4% per year

=> the base number of the exponential function is:

100% - 2.4% = 97.6% = 0.976

Let t is quarter

Let y is the population

=>  the following shows an exponential decay function to find the quarterly decay rate is:

y (t)= 4,200 [tex]0.976^{4t}[/tex]

b. The population is decreasing by how much percent per quarter?

Let t = 0 we have: y(0) = 4,200 [tex]0.976^{4*0} = 4200[/tex]

Let t = 1 we have:  y(1) = 4,200 [tex]0.976^{4*1} = 3811[/tex]

=> the decreasing percentage is:

= (y(0) - y(1)) / y(0)*100%

= (4200 - 3811) / 4200 *100%

= 389/4200*100%

= 9.2%

The expoenetial function that represents the quarterly decay is y = 4200(0.994)^4t.

The  population is decreasing by 0.4% every quarter.

What is the exponential function that determines the rate of decrease every quarter?

The formula that can be used to determine the rate of decrease every quarter is:

FV = P(1 - r/m)^tm

  • FV = Future value
  • P = Present value of the population = 4,200
  • R = rate of decrease = 2.4%
  • m = number of compounding
  • t = number of years

y = 4200( 1 - 0.024/4)^4t

y = 4200(1 - 0.006)^4t

y = 4200(0.994)^4t

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