a city's population decreases at a rate of 2% a year. Given that the population is 150,000. If the rate continues, predict the population of this city in 20 years.

Question

chaotic_butterflies · Answer

How would I set up this problem?

chaotic_butterflies · Answer

@inkyvoyd @mathstudent55 could you help?

brooklynsshaw · Answer

What is 2% off of 150,000?

chaotic_butterflies · Answer

3,000

brooklynsshaw · Answer

Not quite, how did you get your answer?

chaotic_butterflies · Answer

150,000 * 0.02 = 3,000

brooklynsshaw · Answer

Could I send you a link of an example problem to help you out?

brooklynsshaw · Answer

http://jwilson.coe.uga.edu/EMT669/Student.Folders/Rimpley/instuctionalunit/exponents.html

chaotic_butterflies · Answer

I'm not wrong with my calculation though

chaotic_butterflies · Answer

How am I wrong?

brooklynsshaw · Answer

What I did, was take 2 percent off of 150,000, and got 147,000. Then I divided 147,000 by 20, and got 7,350

chaotic_butterflies · Answer

150,000 - 3,000 = 147,000

brooklynsshaw · Answer

Oh, I see what you were trying to tell me now.

peachpi · Answer

You need to use $$A=P(1\pm r)^t$$
Use + for increases and - for decreases.

The 147,000 you're getting is for a 2% decreases after 1 year.
For the population after 20 years, do

$$A=150,000(1-0.02)^{20}$$

chaotic_butterflies · Answer

Thank you, I got it from here @peachpi