A particular pain relieving medicine has a decay rate of 22 % per hour. A patient was given a dose of the medicine 7 hours ago and there is currently 84 milligrams of the medicine in the patients bloodstream.
What was the original dose of the medicine?
How long will the patient need to wait for there to be less than 25 % of the original dose of the medicine left in their bloodstream? Express your answer as a decimal to the nearest tenth of an hour.