Final answer:
It took humanity until about 1800 AD to reach a population of 1 billion, and just over 100 years to reach 2 billion. This illustrates exponential growth, with the population reaching over 7 billion by 2011. At a 1% growth rate, it would take approximately 70 years for the population to double from 7 to 14 billion.
Step-by-step explanation:
Population Growth Milestones
The journey of human population growth to reach 1 billion is a significant chapter in human history. It took until about 1800 AD for the global population to reach 1 billion. The growth pattern from there to 7 billion effectively showcases an exponential model. After hitting the 1 billion mark, it took just over 100 years, more precisely, by 1930, for the population to double and reach 2 billion. This rapid growth continued, with each subsequent billion added in notably shorter periods: 30 years to the third, 15 years to the fourth, 14 years to the fifth, and only 12 more years to reach 7 billion by 2011.
Considering a continuous 1% population growth rate, we can project future population increases. To calculate the time required to reach the next billion at a 1% growth rate, we would use the formula for exponential growth. This shows that it would take approximately 70 years to double the population from 7 to 14 billion if the growth rate remained constant.