Question

1. A car is worth $23000 in Jan 2017 in the first year the car depreciates by 15 percent per annum and then 7 percent every year after that.
a) what will the car be worth in Jan 2023?
b) when will the car be worth $5000?

2. In 2017 the population of a certain animal in your area was counted at 800. you know from recent studies that the population has steadily been decreasing at a rate of 3.5 percent per year.
a) when will the population reach 500 animals?
b) before this steady decline the population had achieved a high of 1200 animals. in what year was that?

Answer 1

1. a) value = (23000 * .85) (1 - .07)^(2023 - 2018)

b) 5000 = (23000 * .85) (1 - .07)^(year - 2018)

2. a) 500 = 800 (1 - .035)^(year - 2017)

b) 800 = 1200 (1 - .035)^(2017 - year)