Set 3: Exponential Functions

Choice A is correct. Choice A is the correct answer. Solve for $r$ when investment quadruples. 1. Equation: $4P = Pe^{15 r}$. 2. Simplify: $4= e^{15 r}$. 3. Natural log: $\ln(4) = 15 r$. 4. Solve: $r = \frac{\ln(4)}{15} = \frac{1.386}{15} \approx 0.0924 = 9.24\%$. Strategic Tip: For quadrupling: $\ln(4) = 2\ln(2) \approx 1.386$. Choice B is incorrect because this rate is too low. Choice C is incorrect because this rate is too high. Choice D is incorrect because this would more than quadruple.