Table of Contents

• Section 1. Exact Doubling Time
• 1: In search of ... the exact doubling time
• 2: Finding doubling time with general numbers
• 3: Logarithms = Exponent-busters
• 4: Test your knowledge of logs
• 5: More exponent busting
• Section 2. Applications
• 6: World Population
• 7: Growth of technology
• 8: How long before the oysters are unsafe?
• Review
• 9: Summary

Exponent busting on your own

So, give that a try on your own.

Let's say the oysters were infected by a single Vibrio at 3 pm, and by the next day at 3pm, when they were harvested, there were 10,000 bacteria per oyster. Assuming exponential growth, how fast was the population doubling?

 

Start with the basic equation for exponential growth:

N_t = N₀ * 2ⁿ

where t means the final number of bacteria.

Here are some hints if you're not sure what to do:

 

Answers

 

You might have noticed that I haven't given you a formula to figure out the doubling time. You could write a formula based on the steps above, but it would be hard to remember, whereas if you understand logs and you follow the exponential growth equation, you WILL get the right answer. Ergo, no formula.