Question

The human population doubles approximately every 50 years. If there were 2.5 million people in 1950, how many people are forecasted to populate the earth in 2050?

Answer 1

From 1950 to 2050 is 100 years, so that would make the population doubling twice in that amount of time. So in 2000 the population would go from 2.5 million to 5 million. And in 2050 the forecast for population would be 10 million.
2.5 x 2 = 5
5 x 2 = 10