1. The problem states that the mice population starts at 25,000 and decreases by 20% each year. 2. To model this, we use an exponential decay function: $$P(t) = P_0 (1 - r)^t$$ where: - $P_0 = 25000$ is the initial population, - $r = 0.20$ is the decay rate (20%), - $t$ is the number of years. 3. Substitute the values into the model: $$P(t) = 25000 (1 - 0.20)^t = 25000 (0.80)^t$$ 4. To find the population after 3 years, set $t=3$: $$P(3) = 25000 (0.80)^3$$ 5. Calculate $(0.80)^3$: $$0.80 \times 0.80 \times 0.80 = 0.512$$ 6. Multiply by the initial population: $$25000 \times 0.512 = 12800$$ 7. Therefore, the mice population after 3 years will be 12,800. The correct answer is c. 12 800.