The amount of caffeine in the body of a healthy adult after drinking espresso decreases exponentially, with a half-life of approximately 6 hours. That is, every 6 hours, the amount of caffeine in the body decreases by 50%. Charlotte wants to go to sleep at 11 pm and does not want more than 20 milligrams (mg) of caffeine in her system at that time. What is the latest time Charlotte can drink a 2-ounce shot of espresso that contains 80 mg of caffeine?
After 6 hours the amount of caffeine 40 mg. After another 6 hours the amount of caffeine is 20 mg. It takes 12 hours for the total amount of caffeine to drop down to 20 mg. the answer is 11 am -B. Hope this helps!
