Question

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Explanation:

Calculate the approximate doubling time

Using the Rule of 70 and Doubling Time knowledge points

$$ T_{\text{double}} \approx \frac{70}{r} = \frac{70}{2.1} \approx 33.33 \text{ years} $$

$$ T_{\text{double}} \approx 33 \text{ years} $$

Calculate the number of doubling periods

Using the Population Trend Prediction knowledge point

$$ \Delta t = 2050 - 2000 = 50 \text{ years} $$

$$ n = \frac{\Delta t}{T_{\text{double}}} = \frac{50}{33} \approx 1.515 $$

Predict the population in 2050

Using the Population Trend Prediction knowledge point

$$ P(2050) = P(2000) \times 2^n = 4.0 \times 2^{1.515} \approx 4.0 \times 2.858 \approx 11.43 \text{ billion} $$

$$ P(2050) \approx 11.4 \text{ billion} $$

Answer:

Question 1

What is the approximate doubling time?
<blank>33</blank> years

Question 2

What will be the approximate population in 2050?
<blank>11.4</blank> billion