Set 14: Exponential Functions

Choice A is correct. Choice A is the correct answer. Use half-life calculation. 1. Half-lives: $\frac{12}{4} = 3$ half-lives. 2. Remaining: $600\times (\frac{1}{2})^3 = 600 \times \frac{1}{8} = 75$ mg. 3. Formula: $A(t) = 600(0.5)^{t/4}$. Strategic Tip: 3 half-lives = $\frac{1}{8}$ of original amount. Choice B is incorrect because this is after 2 half-lives (8 hours). Choice C is incorrect because this is after 1 half-life (4 hours). Choice D is incorrect because this would be after 4 half-lives (16 hours).