The formula Upper D equals 2 0 e Superscript negative 0 . 5 hD = 2 0 e 0 . 5 h can be used
The formula
Upper D equals e Superscript negative hDeh
can be used to find the number of milligrams D of a certain drug that is in a patient's bloodstream h hours after the drug was administered. When the number of milligrams reaches
the drug is to be administered again. What is the time between injections?