If a drug has a half-life of 6 hours, after 18 hours the remaining fraction is:
✓ 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%.
18 hours = 3 half-lives. After each: 1/2, 1/4, 1/8. Remaining fraction = (1/2)^3 = 1/8 = 12.5%.