Suppose the rate at which a rumor spreads - that is, the number of people who have heard the rumor over a period of time - increases with the number of people who have heard it. If y is the number of people who have heard the rumor, the following function, where t is the time in days, is true. dy/dt=ky a) if y is 1 when t=0, and y is 3 when t=2, find k