9. Write an exponential equation describing the given population at any time t. Initial population 2800; doubling time 4 years O A = 2800( 24) O A - 2800 (27/4 O A = 2800*/4 O A - 28004 any time t. 10. Write an exponential equation describing the amount of radioactive material present at Initial amount 500 grams; half-life 30 years O A - 500 1 -1/30 O A = 500 O A = 500-/30 O A - 500-30 11. Assume the pesticide DDT has a half life of 12 years. If 50 pounds were used on a certain field 20 years ago, how much remains? Round to two decimal places. 15.75 16.45 O 17.00 14.35 5