Question

In​ 2012, the population of a city was 5.69 million. The exponential growth rate was 2.87​% per year. ​a) Find the exponential growth function. ​b) Estimate the population of the city in 2018. ​c) When will the population of the city be ​8 million? ​d) Find the doubling time. ​a) The exponential growth function is ​P(t) nothing​, where t is in terms of the number of years since 2012 and​ P(t) is the population in millions. ​(Type exponential notation with positive exponents. Do not simplify. Use integers or decimals for any numbers in the​ equation.)

Answer 1

Answer:

a) The exponential growth function

P(t) = 5,690,000(1.0287)^t

b) 6,742,868.7374 million

c) 12.04 years

d) 2439.0243902

Step-by-step explanation:

In​ 2012, the population of a city was 5.69 million. The exponential growth rate was 2.87​% per year. ​

The formula for exponential growth is given as:

P(t) = Po( 1 + r) ^t

Where P = Population size after time t

Po = Initial population size

r = Growth rate in percentage

t= time in years

a) Find the exponential growth function.

P(t) = Population size after time t

Po = Initial population size = 5.69 million

r = Growth rate in percentage = 2.87% = 0.0287

t= time in years

The Exponential growth function

P(t) = 5,690,000(1 + 0.0287)^t

P(t) = 5,690,000(1.0287)^t

​b) Estimate the population of the city in 2018. ​

From 2012 to 2018 = 6 years

t = 6 years

Hence,

P(t) = Po( 1 + r) ^t

P(t) = 5,690,000(1 + 0.0287)^6

P(t) = 5,690,000(1.0287)^6

P(t) = 6,742,868.7374 million

c) When will the population of the city be ​8 million?

P(t) = 8,000,000

P(t) = Po( 1 + r) ^t

P(t) = 5,690,000(1 + 0.0287)^t

8,000,000 = 5,690,000(1 + 0.0287)^t

8,000,000 = 5,690,000(1.0287)^t

Divide both sides by 5,690,000

8,000,00/5,690,000 = 5,690,000(1.0287)^t/5,690,000

= 1.4059753954 = 1.0287^t

Take logarithm of both sides

log 1.4059753954 = log 1.0287^t

Log 1.4059753954 =t Log 1.0287

t = Log 1.4059753954/Log 1.0287

t = 12.041740264

t = 12.04 years

​d) Find the doubling time.

The formula is given as 70/Growth rate

= 70/0.0287

= 2439.0243902