Table of Contents

• Section 1. Frank's Story
• 1: The story
• 2: Biological interlude
• Section 2. How the meningitis population grows
• 3: How many meningococci can kill you?
• 4: Build the basic growth equation
• 5: Draw exponential growth
• Section 3. So why isn't Frank dead already?
• 6: How long has poor Frank got?
• 7: All we need now is data
• 8: Looking at data
• 9: Log transform straightens out exponential growth
• 10: Do ALL curves get "straightened" by taking the log?
• 11: Phases of bacterial growth
• Section 4. How can we tell when the population is growing exponentially?
• 12: A test for exponential growth
• 13: And the answer is...
• 14: No way its growing that fast!
• 15: Some more practice
• 16: In search of ... the exact doubling time
• 17: Finding doubling time with messy numbers
• 18: Logs = Exponent-busters
• 19: Let's bust some exponents
• 20: Let's bust some exponents
• 21: Extended problem #1: Exponential growth ends (with a whimper)
• Section 5. Back to Frank
• 22: Extended Problem #2: How long DOES poor Frank have?

All we need now is data

We know that bacterial populations grows exponentially (N_t = N₀ 2^t), and we know how many are likely to kill him (2.5 million), and we even know how many generations it will take to get to that number (about 21 generations) but what we don't know is... how fast are the generations? Or, put another way, what is the doubling time?

If the doubling time is a week, or a year, it would take a really long time to get to 2.5 million meningococci, and Frank could take some medicine go home feeling pretty confident. That would still be exponential growth, but it would be very slow. Like molasses.

But if the doubling time is in the seconds or minutes, then Frank is in real trouble.

So, how fast do meningococci populations double? Let's order up some data, stat!