Choice A is the correct answer. Find the growth factor per day.

1. Formula: $P(t) = P_0(b)^t$ where $P_0 = 10$, $P(3) = 80$.
2. Set up: $80 = 10(b)^3$.
3. Solve: $b^3 = 8$, so $b = 2$.
4. Verification: $10(2)^3 = 10(8) = 80$ ✓

💡 Strategic Tip: To find base $b$, isolate $b^t$ and take the appropriate root.

Choice B is incorrect because$10(3)^3 = 270 eq 80$. Choice C is incorrect because this is $b^3$, not $b$. Choice D is incorrect because this is the difference, not the factor.