Answer:
40 years
Explanation:
With the growth of human population from the last century until now, the rate at which growth has excelled is instrumental to the human race.
In 1950, the population of the human race took only 40 years for it to accelerate from an estimated number of 2.5 billion to 5 billion. it is important to note that the average the double figures of the increasing time is lesser than that of the average lifetime of a human being.
Before the end of the 20th century, the population of the world has passed the mark of 6 billion people. it is estimated that before the end of the 21st century, the world's population would increased between 8 to 12 billion.
