A chemical substance has a decay rate of 9.4% per day. The rate of change of an amount N (N of the chemical after t days is given by E = - 0.094N. a) Let N0 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 3 days? c) What is the rate of change of the amount of the substance after 3 days? d) After how many days will half of the original 400 g of the substance remain? a) N(t)= No e "0-09\". h) After 3 days, D 9 will remain. (Round to the nearest whole number as needed.)