The half-life of radioactive lead 210 is 21.7 years. Use this information to construct a function that will model the amount of lead 210 remaining after t years, from an initial amount of 500 grams. A = A0^e^kt a) Find the exponential decay model for lead 210. [5 pts.] b) Estimate how much of the sample of 500 grams will remain after 10 years ?(5pts.) c) Estimate how long it will take a sample of 500 grams to decay to 400 grams (5pts.)