Question

The population of a city grows exponentially at rate of 8% per year.Find the number of years it takes for the population to be doubled Give your answer correct to the nearest whole number

Answer 1

Answer:

It will take 9 years for the population to double

Step-by-step explanation:

Exponential Growth

The natural growth of some magnitudes can be modeled by the equation:

$P=P_o(1+r)^t$

Where P is the actual amount of the magnitude, Po is its initial amount, r is the growth rate and t is the time.

The population of a city grows at a rate of r=8% = 0.08 per year. We are required to find when (t) the population will double, or P=2Po.

Substituting in the equation:

$2P_o=P_o(1+0.08)^t$

Simplifying:

$2=(1.08)^t$

Taking logarithms:

$\log 2=\log (1.08)^t$

Applying the exponent property of logs:

$\log 2=t\log (1.08)$

Solving for t:

$\displaystyle t=\frac{\log 2}{\log (1.08)}$

Calculating:

$t\approx 9$

It will take 9 years for the population to double