Quote Originally Posted by lancelot854 View Post
Two bacteria colonies are cultivated in a laboratory. The first colony has a doubling time of 2 hours and the second a doubling time of 3 hours. Initially, the first colony contains 1000 bacteria and the second colony 3,000 bacteria. At what time t will sizes of the colonies be equal?

We never learned this in class, and he expects us to know it for the next one. I have no idea what to do here. :S
This should tell you that at time $\displaystyle $$ t$ the colony size $\displaystyle N(t)$ is:

$\displaystyle N(t)=N(0)2^{t/t_2}$

where $\displaystyle $$ t_2$ is the colony doubling time and $\displaystyle N(0)$ is the colony size at $\displaystyle $$ t=0$