## oreilly.vincent 2 years ago if a bacteria population triples every three hours, how long will it take a population of 20 colonies to grow to 1,000?

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1. oreilly.vincent

I'm going over practice problems during break and I am stumped on this one. Forgot how to do exponential...The answer in my book says 10.683 hours.

2. xkylex

Thank god its practice, il still try to figure it out

3. oreilly.vincent

yeah i know! but out of everything I am reviewing I am totally missing something here...I'm pretty sure I need to find the rate and then just plug that into the log.

4. xkylex

yeah

5. LogicalApple

Are you familiar with the exponential growth equation \[N = N _{0} e ^{kt}\]

6. oreilly.vincent

yes

7. LogicalApple

Well, we know N0 is the initial population. N0 = 20. This corresponds to time t = 0. We also know that the population, N, triples every three hours. Thus when t = 3, N = 60. Plug these numbers in and solve for k. Then you will have a general equation.

8. oreilly.vincent

awwwwwwww, yes! thank you. i have been refreshed.