Logarithmic Modeling problem

Ok I've been quite stuck on this for a little while and as always, I have the worst time setting up the problem.

An infectious strain of bacteria increases in number at a relative growth rate of 200% per hour. When a certain critical number of bacteria are present in the bloodstream, a person becomes ill. If a single bacterium infects a person, the critical level is reached in 24 hours. How long will it take for the the critical level to be reached if the same person is infected with 10 bacteria?

:confused: I know we use the exponential growth formula but i'm uncertain as to how to set it up with the problem.