Please HELP ME:

In 1990, the rate of change of the world population was approximately 0.09125 billion per year (or approximately 1 million people every four days). The world population was estimated to be 5.3 billion in 1990.

According to the model, when will the population of the world be double the 1990 population?

AThe population will double in approximately 270 years time, by 2260.
BThe population will double in approximately 17 years time, by 2007.
CThe population will double in approximately 58 years time, by 2048.
DThe population will double in approximately 116

The model assumes that the rate of change is constant = 0.09125 billion people/year

Then, the model is y = 5.3 + 0.09125x

Where 5.3 is the population in 1990 and x is the number of years elapsed since 1990.

Double popultaion => y = 2*5.3 = 10.6.

Then 10.6 = 5.3 + 0.009125x => x = 5.3 / 0.009125 ≈ 58

Then year = 1990 + 58 = 2048

Answer: c "The population will double in approximately 58 years time, by 2048"

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