Question

Write an exponential function to model the situation.A population of 300 animals decreased at an annual rate of 22%

Answer 1

`y = 300(0.78)^x`

Explanation:

x is the number of years. y is the population after x years.

Each year, the population decreases by 22%, since 100% - 22% = 78%, and 78% = 0.78, each year, the population is 0.78 of the previous year's population.

year zero: y = 300

year 1: y = 300 * 0.78 = 300 * (0.78)^1

year 2: y = (300 * 0.78) * 0.78 = 300 * (0.78)^2

year 3: y = ((300 * 0.78) * 0.78) * 0.78 = 300 * (0.78)^3

year x: y = 300(0.78)^x