A city had a population of 110,000 in 1920. The population grew at a rate of 1% per year thereafter.

Which function could model this situation?

Use the function you selected to estimate the population in 1922.
Round your answer to the nearest whole number.

1 answer

To model the situation of a city with an initial population of 110,000 in 1920, growing at a rate of 1% per year, we can use the exponential growth function:

\[ P(t) = P_0 \cdot (1 + r)^t \]

where:

  • \( P(t) \) is the population at time \( t \),
  • \( P_0 \) is the initial population,
  • \( r \) is the growth rate (as a decimal), and
  • \( t \) is the number of years since the initial population was measured.

Given:

  • \( P_0 = 110,000 \)
  • \( r = 0.01 \) (which is 1% expressed as a decimal)
  • The initial year is 1920, so \( t \) will be the number of years after 1920.

To estimate the population in 1922, we need to calculate \( P(2) \) (since 1922 is 2 years after 1920):

\[ P(2) = 110,000 \cdot (1 + 0.01)^2 \]

Calculating \( (1 + 0.01)^2 \):

\[ (1.01)^2 = 1.0201 \]

Now, substitute it back into the population model:

\[ P(2) = 110,000 \cdot 1.0201 = 112,221 \]

Rounding to the nearest whole number, the estimated population in 1922 is:

\[ \boxed{112221} \]