Question

In 2016 the United States had a population of about 323 million people and was growing at 0.7 %. Use an explicit exponential model to predict what year the U.S. population will reach 400 million people

Answer 1

Answer:

2047

Step-by-step explanation:

We are given that

Growing rate=0.7%

$\frac{dp}{dt}=\frac{0.7}{100}P$

$\int \frac{dP}{P}=0.007\int dt$

$lnP=0.007t+C$

Using the formula

$\int \frac{dx}{x}=ln x+C$

$P=e^{0.007t+C}=e^{0.007t}\cdot e^C=Ae^{0.007t}$

$e^C=A$

Initially when t=0,P=323 million

Substitute the values

$323 million=A$

$P=323e^{0.007t}$

Now, substitute P=400 million

$400=323e^{0.007t}$

$ln\frac{400}{323}=0.007t$

$ln(1.2384)=0.007t$

$t=\frac{ln(1.2384}{0.007}$

$t=30.5\approx 31 Years$

Year=2016+31=2047

Hence,In 2047 the U.S population will reach 400 million people.