Suppose the population of a town is 500,000 in 1990. The population increases at a rate of 5% every five years. What will be the population of the town in 2005? Round your answer to the nearest whole number.

Question

blurbendy · Answer

You need to make use of the formula:

Future population = P[(1+r)^t

where P is the current population
r = 0.05 (represents the rate of 5%)
and t = 15/5 (represents 15 years, but the population increases 5% every 5 years)

blurbendy · Answer

Make sense?

anonymous · Answer

Yes, I got 62.5 so do I just add that to the original population?

blurbendy · Answer

I didn't get 62.5.  I entered this into my calculator:

500000(1+r)^3

blurbendy · Answer

where r is .05

anonymous · Answer

I put that too :/ I don't know what I'm doing wrong then

blurbendy · Answer

be careful with your parentheses maybe? here's what google says, and is what I got: https://www.google.com/#output=search&sclient=psy-ab&q=500000%281%2B.05%29^3&oq=500000%281%2B.05%29^3&gs_l=hp.3...1066.5697.0.5911.15.14.0.1.1.0.164.1510.7j7.14.0....0...1c.1.21.psy-ab.zT60Kzt-IHY&pbx=1&bav=on.2,or.r_qf.&bvm=bv.49478099,d.cGE&fp=fd4d64e276b844ed&biw=1440&bih=745

anonymous · Answer

Wait, wouldn't t=3?? Because if you subtract 2005 from 1990 you get 15 and then you divide by 5 since it's every 5 years

blurbendy · Answer

yes that's why we have:

500000(1+r)^3

t = 3

anonymous · Answer

oh sorry I read that wrong, in my notes the equation did not have the 1+r it was just r in parentheses

blurbendy · Answer

so what answer did you get now?

anonymous · Answer

Same answer as you, thanks!

blurbendy · Answer

good job!