A patient is given 800 mg of Ibuprofen. The average half-life of Ibuprofen is about 1.8 hr. Write an exponential model of the form P(t) = P_0e^{kt} that represents the amount of Ibuprofen in the patient's bloodstream in t hours after the medicine is administered. Round the value of k to five decimal places. Then use the model to determine how much Ibuprofen will be in the patient's bloodstream after he is given a second dose of 800 mg in 4 hr after the first dose. Round your answer to two decimal places