4. During a chemistry lab. students were asked to study a radioactive element which decays over time. The results are in the table. Time (in days) 8 10 Element (in grams) 320 228 160 115 80 57 13 a) Give the equation which models the remaining mass of the element (Reminder, we are in chapter 9). 14 Use your model to find the predicted amount of the element remaining after 9 days. Show our work. 1 5 9) Find the residual for 8 days