dịch bài                                                        The population of the world has  more in modern time than in all other ages of history. The world's  was about 500 million in 1650. It doubled in the period from 1650 to 1850. In 1986, the population was  three billion. Estimates based on the research  the United Nations in the same year showed that it would be more than 7.5 billion by 2020. Exactly, it was about 7.8 billion in 2020. The UN projected population to keep growing, and  have put the total population at 8.6 billion by mid-2030, 9.8 billion by mid-2050 and 11.2 billion by 2100.