Question

According to the 2000 Census the population of Canton was 7,720. Holly Spring's population was 3,200. Canton's population increases at a rate of 80 people a year and Holly Spring's population increases by 120 people a year. Which equation may be used to determine the number of years before the populations are equal?

Answer 1

Firstly, the rate of increase of Canton = 80/7720 = 0.010
The rate of increase of HP = 120/3200 = 0.0375
Apply  the formula of compound interest==> A =A'(1+i)^n
The population will be equal when the following equality is satisfied

7720(1+0.01)^n = 3200(1+0.0375)^n

or

7720x1.01^n = 3200x1.0375^n

Divide both sides by 3200 ===>(193/80)x1.01^n=1.0375^n

Answer 2

Answer:

the answer would be  D) 7720 + 80x = 3200 + 120x

Step-by-step explanation: