Math help please!!!?

Question

In 1990 the population of new orleans, lousiana was about 497,000 and was decreasing by about 6,000 a year. The 1990 population of phoenix, arizona was about 983,000 people and was decreasing by 20,000 people a year.

a) If these trends had been going on for some time, how many years before 1990 did each city have the same population?

b) What was this population?

Answer 1

As the rate of decrease of the smallest city is less than the rate of decrease of the larger city, the population was never, in the past the same.  Look at it this way - 10 years ago, NO was 60K larger and Pheonix was 200K larger. The gap between the two, in population increases as time goes back.

If you meant to say increasing (a much more likely scenario since at that rate the cities were in the billions centuries ago) then the formula would be:

X = initial population

Y = number of years to present

Using thousands of population ....

x + 6y = 497 which leads to x = 497 - 6Y (NO)

x + 20y = 983 (Ph)

497 + 14y = 983

14y = 983 - 497 = 486

y  = 486/14 = 34.7 or so.

Substituting back in subtract 34.7*6 from 497 or 34.7*20 from 983 to get initial population

Answer 2

a) 34.7 years after 1990, a.k.a.period from 2024 to 2025.

b) 288714

Answer 3

Well, I'm not even going to attempt this but I can direct you to a couple of great websites that can help:

- mathspot.com

- libraryspot.com

Good luck!