Assume that for the certain drug, given the dose of 10 milligrams amount A(t) remaining in body t hours later is provided by A(t) = 10(0:8)t milligrams and that in order for the drug to be efective, at least two milligrams should be in body. Find when (in terms of hours from administration) 2 milligrams remains in body. Determine half life of the drug?