If a drug has a half-life of 6 hours, after 18 hours the remaining fraction is:

A 1/4

B 1/8

C 1/2

D 1/16

✓ Correct Answer: Option B

18 hours = 3 half-lives. After each: 1/2, 1/4, 1/8. Remaining fraction = (1/2)^3 = 1/8 = 12.5%.

💡 Why is B) the correct answer?

The correct answer to the question "If a drug has a half-life of 6 hours, after 18 hours the remaining fraction is:" is Option B: 1/8.

The other options — A) 1/4, C) 1/2, D) 1/16 — are incorrect for this PCAT Exam Prep question. As explained above: 18 hours = 3 half-lives. After each: 1/2, 1/4, 1/8. Remaining fraction = (1/2)^3 = 1/8 = 12.5%.

📚 About This PCAT Exam Prep Practice Question

This 2-level PCAT Exam Prep question from the Quantitative Reasoning topic is part of BrainForge Quiz's free exam preparation library. Each question includes the correct answer and a detailed explanation to help you understand the underlying concept, not just memorize the answer.

How to use this page: Read the question above, consider all four options (A through D), then check the highlighted correct answer and explanation. For active timed practice, start a free PCAT Exam Prep practice test or use flashcards for spaced repetition review.

Practice PCAT Exam Prep Quizzes → Browse All Questions Study Flashcards

If a drug has a half-life of 6 hours, after 18 hours the remaining fraction is:

✓ Correct Answer: Option B

📚 About This PCAT Exam Prep Practice Question

Related PCAT Exam Prep Questions