1) A drug is eliminated from the body through urine. Suppose that for an initial dose of 10 milligrams, the amount A(t) in the body t hours later is given by A(t) = 10(0.9)t.
(a) Estimate the amount of the drug in the body 7 hours after the initial dose. (Round your answer to two decimal places.)
(b) What percentage of the drug still in the body is eliminated each hour?
2.1) An exponential function W such that W(t) = W0ekt for k > 0 describes the first month of growth for crops such as maize, cotton, and soybeans. The function value W(t) is the total weight in milligrams, W0 is the weight on the day of emergence, and t is the time in days. If, for a species of soybean, k = 0.3 and W0 = 69 mg, predict the weight at the end of 25 days. (Round your answer to the nearest mg)
2.2 ) It is often difficult to measure the weight W0 of a plant from when it first emerges from the soil. If, for a species of cotton, k = 0.21 and the weight after 10 days is 725milligrams, estimate W0.