A bacteria culture starts with
420
bacteria and grows at a rate proportional to its size. After
4
hours there will be
1680
bacteria.

(a) Express the population
P
after
t
hours as a function of
t
.
P
(
t
)
=

(b) What will be the population after 2 hours?
bacteria

(c) How long will it take for the population to reach 1510? Give your answer accurate to at least 2 decimal places.
hours