Choice A is the correct answer. Find when value doubles.

1. Formula: $V(t) = 0.50(1.15)^t$, solve for $1.00 = 0.50(1.15)^t$.
2. Simplify: $(1.15)^t = 2$.
3. Test:
   • $t=4$: $(1.15)^4 \approx 1.749$ (below 2)
   • $t=5$: $(1.15)^5 \approx 2.011$ (above 2) ✓
4. Answer: Between 4 and 5 weeks.

💡 Strategic Tip: Rule of 72 gives rough estimate: $\frac{72}{15} \approx 4.8$ weeks.

Choice B is incorrect because doubling happens sooner. Choice C is incorrect because growth is much faster. Choice D is incorrect because$(1.15)^2 \approx 1.32 eq 2$.