a. If $15,000 is invested at an interest rate of 2% per year, compounded semiannually, find the value of the investment after 6 years.

b. If $1000 is invested at an interest rate of 3.5% per year, compounded continuously, find the value of the investment after 3 years.

c.When a certain medical drug is administered to a patient, the number of milligrams remaining in the patient's bloodstream after t hours is modeled by

D(t) = 40e^0.1t.

How many milligrams of the drug remain in the patient's bloodstream after 4 hours? (Round your answer to one decimal place.)

*please show all equations and steps, I need help understanding