< Question 4, 2.5.1-PS Part 1 of 4 > HW Score: 13.16%, 5 of 38 points Points: 0 of 1 Save A chemical substance has a decay rate of 8.2% per day. The rate of change of an amount N of the chemical after t = -0.082N. days is given by dN dt a) Let No represent the amount of the substance present at t = 0. Find the exponential function that models the decay. b) Suppose that 400 g of the substance is present at t = 0. How much will remain after 6 days? c) What is the rate of change of the amount of the substance after 6 days? d) After how many days will half of the original 400 g of the substance remain?