Question

in 2017, the estimated world population was 7.5 billion. use a doubling time of 45 years to predict the population in 2025, 2071, and 2119.

what will the population be in 2025?

the population will be billion.
(round to one decimal place as needed.)

Explanation:

Define the exponential growth model

Using the Exponential Growth and Doubling Time knowledge points

$$ P(t) = P_0 \cdot 2^{\frac{t}{T_d}} $$

$$ P_0 = 7.5,\quad T_d = 45 $$

Calculate elapsed time for 2025

Using the Absolute Change knowledge point

$$ t = 2025 - 2017 = 8 $$

Compute the predicted population

Using the Exponential Growth knowledge point

$$ P(8) = 7.5 \cdot 2^{\frac{8}{45}} $$

$$ 2^{\frac{8}{45}} \approx 2^{0.17778} \approx 1.1311 $$

$$ P(8) \approx 7.5 \cdot 1.1311 \approx 8.483 $$

Round to one decimal place

Using the Absolute Change knowledge point

$$ P(8) \approx 8.5 $$

Answer:

What will the population be in 2025?

The population will be <blank>8.5</blank> billion.
(Round to one decimal place as needed.)