Answer to Carries Question

For 11, I set up the system according to the way we did the Britney Spears question in class.

11 = a * b^10
26 = a*b^15

I then solved fo r b and got b = the fifth root of (26/11). After this I found the amount of people who heard the rumor when the time was zero.

We can re-write the equation as f(t) = a * (26/11) ^ (t/5). We know that the amount of people who heard the rumor at t = 10. So we can divide the amount of people who heard it then (11) by 26/11. This gets us the value when t = 5. We then divide the people who heard the rumor when t = 5 by 26/11. Now we have found the value of a.

The exponential equation of the problem should be:

f(t) = 1.96894 * (26/11) ^ (t/5)

Now, just find f(31). I hop this is right Carrie and everyone else, if it is not please tell me so I don't get it wrong too.