The number, n, of people who have heard a rumor spread by mass media at time, t, is given by n(t)=a(1−e−kt). there are 500000 people in the population who hear the rumor eventually. 21 percent of

The number, n, of people who have heard a rumor spread by mass media at time, t, is given by n(t)=a(1−e−kt). there are 500000 people in the population who hear the rumor eventually. 21 percent of them heard it on the first day. find a and k , assuming t is measured in days.