9514 1404 393
Answer:
about 3,160,000,000
Explanation:
"Increases at a rate proportional to population" means the growth is exponential. It can be modeled by the equation ...
p = ab^t
We can find 'a' and 'b' using the given data points.
100 = ab^(-4) . . . . . . . population 4 days ago
100,000 = ab^(-2) . . . population 2 days ago
Dividing the second equation by the first, we find ...
1000 = b^2
b = 1000^(1/2)
Substituting for b in the first equation, we have ...
100 = a(1000^(1/2))^(-4) = a(1000^-2)
100,000,000 = a
Then the population model is ...
p = 100,000,000×1000^(t/2)
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Tomorrow (t=1), the population will be ...
p = 100,000,000 × 1000^(1/2) ≈ 31.6 × 100,000,000
p ≈ 3,160,000,000 . . . . . bacteria by tomorrow
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Additional comment
We could write this as ...
p = 10^(8+1.5t)
Then for t=1, this is p = 10^(8+1.5) = 10^0.5 × 10^9 = 3.16×10^9