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You and your lab partner wish to determine the concentration of a bacterial broth culture. You...

You and your lab partner wish to determine the concentration of a bacterial broth culture. You dilute the culture by 1:1,000,000 (or 10-6). You then pipet 1 ml into a Petri dish and pour melted TSA on top of it. After gently swirling to mix and allowing it to harden, you incubate overnight at 37° C. The next day you count 95 colonies on the plate. What is the concentration of the original culture in CFU/ml?

How would your answer to the problem above change if you had added 0.1 ml to the agar plate instead of 1 ml?

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