Decay of radioactive materials can be modeled by the equation A=A0*e^(kt) where A is the amount at time t, A0 is the amount at t=0 and k is the decay constant (k <= 0). Iodine-132 is a radioisotope that is used in thyroid function tests. Its half life time is 13.3 hours. Calculate the relative amount of iodine-132 (a/a0) in a patient's body 48 hours after receiving a dose. After determining the value of k, define a vector t= 0, 4, 8, ..48 and calculate the corresponding value of a/a0.