Set 12: Exponential Functions (Intermediate)
Explanation
A phone's battery percentage follows where is hours. After how many hours is the battery at 50%?
Between 8 and 9 hours
Exactly 50 hours
Between 2 and 3 hours
After 10 hours
Detailed Explanation
Choice A is correct. Choice A is the correct answer. Solve . 1. Simplify: . 2. Test Values: - : (above 0.5) - : (below 0.5) 3. Conclusion: Answer is between 8 and 9 hours. Strategic Tip: For SAT, estimation and testing values is often faster than logarithms. Choice B is incorrect because 50 is the target percentage, not the time. Choice C is incorrect because the decay is too slow for this short time. Choice D is incorrect because by hour 10, battery would be below 50%.
Key Steps:
The correct answer is Between 8 and 9 hours
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