Final answer:
Using an exponential decay function to model the decline in a rare deep water fish population, the estimated number of fish after six months is approximately 310, which is closest to answer choice A. 249 fish.
Step-by-step explanation:
The question deals with an exponential decay of a rare deep water fish population. To find the number of fish after half a year (six months), we use the function that represents exponential decay:
Initial amount, A(0) = 821 fish
Decay rate per month, r = 15%
The function to model this decay is:
A(t) = A(0) × (1 - r)^t
For half a year (t = 6), the function becomes:
A(6) = 821 × (1 - 0.15)^6
Calculating the value,
A(6) = 821 × (0.85)^6
A(6) = 821 × 0.377149
A(6) ≈ 310 (rounded to the nearest whole number)
Since none of the multiple choice answers exactly matches our calculation, there might be a misunderstanding or a typo in the question. However, if we're to choose the closest value, the answer would be: Answer: A. 249 fish (though the actual calculation gives us approximately 310 fish)