When a drug is discontinued, what percentage of that drug will remain in the body after three half-lives?

About 12.5%

Explanation:

Every half life usually eliminates about half or 50% of drugs that is stored in the body system.

Therefore, after one half life, the percentage of drug stored in the body will be 50%, after two half lives it will be reduced by 50% which is 25%.

After three half lives, the percentage of drug stored in the body will also be eliminated by 50% which will be half of 25% and it will be 12.5%.

Therefore, the answer is 12.5%.

sound moves fastest in solids because the molecules are tightly packed and it allows sound to vibrate