Question

what is mean by doubling time? Has it gotten longer or shorter for the world's population? Cite and use actual numbers in your answer.

Answer 1

Ans:

1. The doubling time is thetime period that is nessesery for a quantity to double in size or value. It is applicable to each all of the population growth, inflation, resource extraction, consumption of goods, compound interest, the volume of malignant tumours, in short anythings that tend to grow over time. When the rate of the relative growth is constant, the quantity grows exponentially and has a constant doubling time or period, which may be calculated from the growth rate. This doubling time can be calculated or approximated by dividing the natural log of 2 by the exponent of growth, by dividing 70 by the percentage growth rate.

For example, net population growth of Canada is 0.9% in the year 2006, dividing 70 by 0.9 which representing a doubling time of 78 years. So if the growth rate remains constant, The population of Canada would be double from its 2006 value of 33 million to 66 million by 2084.

2. The natural growth rate and the world's current growth rate is about 1.14%, which gives an approximate doubling time of 61 years. If current growth continues we can expect that world's population will become from 6.5 billion to 13 billion by 2067. The peaked of world's growth rate was seen in the 1960s at 2% and a doubling time of 35 years.