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
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