In 1925, the population of a city is 90,000. Since then, the population has increased by 2.1% per year. If it continues to grow at this rate, what will the population be in 2020?

Question

In 1925, the population of a city is 90,000.  Since then, the population has increased by 2.1% per year.  If it continues to grow at this rate, what will the population be in 2020?

wolf1728 · Answer

It starts at 90,000 and increases by 2.1% per year which can be shown as
Population = 90,000 * (1.021)^years
Where years = 0 for 1925
1 for 1926, etc
Can you solve for 2020?

mathmale · Answer

Exponential growth.  You could use an equation of the form$$P=P _{0}(1+r)^n$$when the annual growth rate is given.

sphott51 · Answer

its 95 years? like 2020 - 1925

wolf1728 · Answer

Yes, it is 95 years.

anonymous · Answer

Well done mathmale and wolf1728.  I wish I were as quick in typing.

wolf1728 · Answer

Can SPHott51 handle that equation?

wolf1728 · Answer

Hello Directrix

sphott51 · Answer

I got 648,168.62 but I think that is impossible for population if you round it, ccan't be half a person so it just 648,168

wolf1728 · Answer

That is precisely the answer.  You solved the equation correctly :-)

wolf1728 · Answer

Actually it would round to 648,169 but close enough LOL

directrix · Answer

648,168.62 when rounded - would that be 648,168  or 648,169?

Would .62 be counted as a whole person? I don't know.

wolf1728 · Answer

Yes, should we truncate or round - decisions, decisions.  LOL

wolf1728 · Answer

Gee SPHott isn't here anymore

wolf1728 · Answer

Hmm someone is asking a half-life question.

directrix · Answer

If the question has options, it would be nice to see them. :)

sphott51 · Answer

It would be rounded if it wasn't a person or like living thing like an animal.

directrix · Answer

Options (maybe)

A. 4,073,333   	B. 136,382   	C. 648,1659   	D. 6.6x1012

directrix · Answer

@wolf1728     

>>Actually it would round to 648,169 

You are correct!