The drug is eliminated from body through urine. Assume that for the dose of 10 milligrams, amount (A)t remaining in body t hours later is provided by (A)t 10(0.8)^t and that in order for drug to be effective, at least 2 milligrams should be in the body.
a. Find when 2 milligrams is left in body.
b. Determine the half-life of the drug?