11. Suppose there is an initial amount of a radioactive element of 57.89 grams present in the wilderness of Tunisia. The half-life of this radioactive material is 717 years. a. Write the equation that models this situation. b. What is the decay rate of the radioactive material (round your answer to 8 decimal places)? c. How much of the substance will be present after 1500 years (round to four decimal places)? d. When will there be 10 grams of this radioactive material present (round to the nearest whole number)