Final answer:
The fish population after 4 years is approximately 15,000 fish.
Step-by-step explanation:
To determine the fish population in the lake after 4 years, we will substitute t = 4 into the given population model function p=18/(1+4e⁻⁰.⁷ᵗ). Calculating this, we get p=18/(1+4e⁻⁰.⁷(4)). After computing the exponent and the division, we round to the nearest whole number as instructed.
The fish population after 4 years can be found by substituting t = 4 into the given population function p = 18/(1 + 4e^(-0.7t)).
So, p = 18 / (1 + 4e^(-0.7*4)) = 18 / (1 + 4e^(-2.8)) ≈ 14.517.
Since the population is measured in thousands, we need to round the answer to the nearest whole fish. Therefore, the fish population after 4 years is approximately 15,000 fish.