Tobias sent a chain letter to his friends, asking them to forward the letter to more friends. The number of people who receive the email increases by a factor of
4
44 every
9.1
9.19, point, 1 weeks, and can be modeled by a function,
P
PP, which depends on the amount of time,
t
tt (in weeks).
Tobias initially sent the chain letter to
37
3737 friends.